In my experience, unless U2 will net you a punish, that you can react to, against a move that you couldn’t otherwise punish, it is not worth using U2.
Also, if they have a way to escape a properly spaced U2 used at the end of the round for chip, its not worth using U2.
So, while I agree with the use of U2 vs. Ryu/Sagat/ibuki/ken, I doubt its worth taking over U1 in most other matchups.
For Akuma/Sim/Chun/Juri my experience has been that maximizing damage while the opponent is cornered is worth much more than putting a stop to fireball zoning since these characters have such low life and hitting with U2 completely destroys whatever spacing you had before using it. Also, vs. Akuma its important to note that you can’t chip kill with U2 because he can teleport, and chipping at the end of the round is imo a primary use for this Ultra.
vs. Fei I think the only reason you’d be picking U2 is for the chip kills and nothing else…
vs. Bison I’d rather be picking U1 because the only use for U2 is after a blocked ex PC, which you can punish anyways.
vs. Viper This is a tossup, but being able to react with U2 to any burn kick is a huge plus, but then again U1 in this matchup is still as effective as ever, I’d rather take U1.
vs. Hawk/Gief The only reason I pick U2 in these matchups is for chip kills. You won’t be landing dive kicks or putting on corner pressure if the hawk/gief player knows what they’re doing, so might as well give yourself a free 5-10% room for error by taking U2 and chipping their life away at the end of the round.
vs. Vega This matchup is one of the worst in the game, and he has no answer to corner pressure and has low life. I pick U1 vs. akuma/sim/chun just cause they have low health, vs. Vega I see no reason at all for you to be picking U2. j.rh into U1 if you’re really afraid of wall dives :S Either way you should be winning this matchup.
vs. Fuerte U2 if you like to mash, still a hard matchup for fuerte.
vs. Honda U2 just isn’t worth it vs. a good honda. You want to maximize dmg and make your corner pressure more scary with U1 around. If you’re picking U2 its for countering poorly spaced neutral jump fierce, terrible headbutts (which you can punish anyways or dodge and completely destroy) and to kill with chip. If the opponent is good enough to not give you the free damage, then your U2 is reduced to a chip dmg ultra again, except honda is a character that you’ll be pressuring enough to make U1 worthwhile.
vs. Cammy Again, I don’t see the importance of U2 in this matchup. U2 isn’t going to stop her mixup game, imo its just an excuse to do wakeup ultra :S