Donpachi is good, but I'll argue that Gunfight is the most well rounded and consistent Alex I've seen play. Gunfight mentions that Donpachi has had struggles and lost ranks in the updated version of Alex.
I agree with a lot of that you say here. It really comes down to how you play neutral with this character vs. the cast who have other meaningful ways in with fairly minimal risk to them.
Laura - fireball, bolt charge Birdie - V-Skill can Mika - dropkick charge, Zangief - multiple armor normal attacks, iron body
Notice these four characters I've chosen and look at their archetype. In some form, they're grapplers. But what really shines is the fact that once any of them put their opponents into a corner, they receive some form of great Oki, like another command grab, meaty, or another mix-up which on the other side is much more difficult to manage depending on the type of character you play.
So taking a look at the grabs of Alex. Scenarios listed are corner specific.
Backdrop (EX) - situational; micro step power bomb, one meaty -> neutral Power Bomb (EX) - meaty roundhouse, LK Slash Elbow - in but turn is lost in both scenarios Normal grab - micro step power bomb, one meaty -> neutral Back grab - same as above but less plus
In comparison to a few of these characters, I'd say the only Alex competes with the best on pressure is Birdie. Laura, Mika, and Gief show dominance in the corner and outclass him greatly, in my opinion.. Birdie has been dropped off my some, but with Problem X's showing at Sonic Boom, things might change in people sleeping on him.
I definitely acknowledge that it takes but one or two combos in order for him to get back in the fight. Not blind to that at all, but if people couldn't decipher which Slash Elbow was used in S1 and couldn't punish it because of distance, that's on them. Alex players who didn't meaty that attack got blown up properly because of badly spaced Slash Elbows to get in. Currently, the only character you can get away with this on, is Karin; a (non) meaty LK Slash Elbow will not get punished because of stubby lights.
A reliable anti air would be nice, especially need that for Claw, because, unlike Dictator, he has a grab from the air you can't parry in various positions