Other Drive Techniques
Drive Parry (MP+MK in neutral) is basically equivalent to a block button; it defeats high/low and left/right at the initial cost of 1/2 a drive bar and you can cancel into block at any time (so punishing parries with attacks is impossible). But, it doesn't alter frame advantage compared to blocking the move, and doesn't let you drive rush until your "parry stun" wears off. Its main weakness is to throws, where you take SPD-like damage (Ryu's throw did 205 damage on punish counter) and you lose 1 full bar of drive. You also can't tech during parry recovery making throws guaranteed, and if the opponent doesn't attack, you'll just throw away half a bar for no real reason. Successful parries on non-projectiles build back a ton of drive bar very quickly though; I believe parrying all three hits of Luke's LP MP HP target combo built back close to 3 bars of drive.
Parry is a mechanic that will need considerably more matches to be fully worked out. You will probably need parry to fight back against strong projectiles, even just as a holding pattern (since parrying projectiles is meter neutral), and when you're down to 2 or so drive bars, even parrying just two normals during pressure will really help your drive recover. However, you run the risk of being burned out by a punish counter throw, so it's not foolproof. Even if you try to parry the drive rush low/overhead mixups, one of the more reasonable use cases of it, you can cancel drive rush into throw instead so you aren't safe.
Perfect parry, which much more closely mimics a traditional FG parry in games like 3rd Strike, is the same input as Drive Parry, but you must press the buttons at most 2 frames before being hit. Unlike regular parry, it has virtually instant recovery, which means after perfect parrying a jab, you can punish counter with even heavy attacks, although the combo is scaled to 50%. I think most perfect parries will happen in pressure situations where someone blocks a normal and is between -1 and +1, and then either the defense tries to perfect parry more pressure, or the offense tries to perfect parry the defender mashing jab. The fact that all perfect parry attempts can be OSed with blocking or a regular parry means the only risk is being thrown (although, during point blank pressure, this is actually a pretty big risk).
Interestingly, unless you are low on drive or trying to perfect parry offense or zoning, I don't think you'll have much use for guessing parry in neutral. If no mixup is coming your way, you don't gain the benefit of the "super block" (that is, blocking both high and low), and all you're doing is throwing away drive gauge while also locking yourself in place, unable to walk, and making yourself really vulnerable to throws (for example, parry rush into throw on reaction?) for no real gain. If an opponent sees that you try to parry often, what's to stop them from just doing a big plus-on-block move right into your parry and forcing a mixup? You can't walk or jump out of the way, and you can't attack or drive impact to interrupt. Your only choice is to parry or block the move, which leads to the same frame advantage. So I don't really see a benefit here unless you're low on drive and want the drive recovery, you're hoping for perfect parry, or you absolutely must block a scary mixup.
I think EX moves are pretty well costed at 2 bars. Not much to say here, other than I quite like that they separated EX from supers (more on that later). Being able to do both supers and EX moves in the same combo, like 3rd Strike, will be fun.
Drive rush, the green dash cancel, is the other big use of drive meter. I think normal canceled into drive rush is the right cost at 3 bars. It's way too potent during pressure or footsies to be any cheaper.
If you asked me before the beta which system mechanic was too strong, I would have guessed neutral parry canceled into drive rush (what are we calling this? "parry rush"? just "drive rush"?). At only 1 bar cost, and the follow-up normal gaining +4 advantage on hit or block, it felt like it could be clearly the best use of bar at all times. And, well, I think it is the best use of drive, but I think it should remain 1 bar cost, at least at SF6's launch, for a few reasons:
1) Projectiles and normals are so incredibly strong, and parry rush loses to them, so it's harder to use in neutral than it first seemed. They might be relegated only to situations where you've convinced your opponent not to press, or to "guaranteed" setups like after knockdown.
2) Normals are weak in pressure, so spending 1 bar to get a plus frame mixup seems fair if you can manage it, and all of the options that gain the +4 advantage (that is, all normals) can be parried to nullify any high/low mixup (and some will outright lose to drive impact). If this was drastically more expensive, it might not be able to play its part as a nice counter-role to all the space control SF6 has. Also, it may be possible to reversal on reaction to the green flash if someone tries to meaty you with a drive rush normal; more testing needs to be done here to understand what kind of fake outs the offense has.
3) The combos that involve parry rush after a high launcher (since normals used out of rush give extra juggle points) look very cool and should be incentivized; any cost more than 1 bar will make these combos too expensive. One of my wishes for the combo game in SF6 is that these combos are commonplace in real matches and not merely just combo video material. If it turns out that there's not enough incentive to do it after SF6 launches, I hope they make some tweaks to make these combos more attractive to do in matches. They're fun to watch, more difficult to execute than regular links, tempt people to spend more drive which puts them closer to burnout, and will give cool variety.
Also, I want to briefly mention that I like the decision to have chip damage come off the drive bar. You actually lose a lot of drive to chip if you just sit there and block, something that might not be apparent if you were just watching matches instead of playing. But it also means that if you escape and your drive recovers, you actually take 0 damage from zoning or blocking corner pressure. The drawback though is that if you get burned out, you'll almost certainly take considerably more damage than the sum of the chip damage would have been in other SF games. So it's kind of an all-or-nothing approach that I think works for this game, and I like that you can have a "drive life lead" and grind people down this way, forcing them into bad decisions even though they actually haven't lost any health (yet).
Overall, I quite like pretty much every decision they've made for the drive system. It's clear they've thought about it a lot, and in many ways drive is equally important to your health bar. If you have 40% life but full drive, and your opponent has 80% life but 0.5 drive, I'm not entirely sure who's winning here. It's also quite easy to advise beginners on how to use this system at first; do some drive impacts and some EX moves semi-randomly and ignore the rest. It's a deep system that won't get in the way of learning basic concepts of Street Fighter.
Of course, SF6's drive system could be broken at launch as people uncover more about how it works, option selects, etc. But this system seems so easily tweakable that there is undoubtedly an excellent iteration of this coming somewhere in SF6's life. It's much easier to tweak a system that is fun at its core than trying to inject fun into a lifeless, fundamentally broken system, and they're starting with the right core.