For me, the heart of the issue with PES is just how on-rails and basic it all is. Yes, those basics (e.g. ball physics) may be fantastic, but comparing footage of a PES goal (as in, the entire move) to a real goal, and it's all just straight-line passing, very little hustle/bustle and a booming shot.
FIFA has lots of little systems going on at once, and yeah that means you get some wacky animations (and I don't like the rubberyness of it either), but I'd argue that's a lot closer to reality. I see a goal in FIFA, compare it to reality (the speed and urgency of runs, the aggression in the defending, the clashing together, the variety in everything) and I think "wow".
Both games are, at their core, the embodiment of themselves. PES is PES, FIFA is FIFA. But if you've had a year off I reckon you might come to FIFA with a clean slate (in terms of how a football game is "supposed" to feel - a lot of us have that ingrained, and anything else doesn't feel right).
The PES AI patch won't fix the on-rails'ness of everything, so it won't be enough for me personally. FIFA patches may ruin the game offline - but you know what, given the change from demo to beta to retail (fast and not great, to good, to great)... I'm giving them the benefit of the doubt this time.