Er, actually, Guilty Gear has one of the larger input buffers in all of fighting games. There's plenty of command leeway. Frame-perfect timing only comes in on stuff like links and really short FRCs and stuff like that.
But yeah, it'll feel like that coming from Blazblue because that game is in slow motion.
Well yeah, but we're talking about difficulty here. Saying "I can be on the offensive all the time and get big combos and win" is true for like... 80% of the cast, assuming you can actually stay on the offensive the whole match and do big combos and win. I speak from experience when I say that when I'm playing someone who can't really do defense or doesn't know how to get around my character, I can just walk all over them, crank their guardbar, do giant combos, and make them go cry in the corner, and I don't need ABA to do it. But if you play someone who knows how to stop ABA cold and make her get hurt for trying, she just has more things to worry about. You can't do OTG keygrab combos if you can't get a combo off, and even if you run away and bloodpack, at least a good portion of characters can chase you down for it, and the ones that can't get to set up and make it tough for you to get back into Moroha mode. And that's assuming you can get out of THEIR offense in the first place. In a case where you just get to do whatever you want and your opponent doesn't know how to stop you, any character is easy.
(DISCLAIMER: I don't play ABA, but I've played AGAINST a few. I'm not saying I always win either. Moroha, for example, is tough, but that's mainly because he knows what he's doing.)
Agree, although I'll add that one major issue going to MB for even GG players is VERY low hitstop. This makes even chain combos harder to confirm/connect than in GG/especially BB.