In stock, good Japanese play means not surrounding and eliminating units until Chungking falls.
I doubt this can be done. To take Chungking, you need two things : get there (obviously) and keep your supply lines open. You won't achieve the latter with a lot of KMT units roaming free behind the front. And if you push them before you, you will find them in Chungking anyway.
In my game, I tried to be prudent with "needless elimination", managed to trap all the Changsha garrison, and left big stacks of depleted defenders in the mountains between Shaanxi and Sichuan. Yet many units were eliminated in the process, and we now have 120 units in Chungking, half of them respawned (for some reason, every unit seems to respawn, not just infantry)...
But it doesn't really matter. Respawned units eat most of the supplies anyway, and once the forts are down things get bad very fast for the KMT. It is just that, in stock, after all of China is defeated, you still need several months to finish Chungking off (not sure how many, I think I will manage four in my game, but then, I had underestimated this part of the war).
With stacking limits, you probably need more time to break through, but once Chungking is surrounded, it might fall faster. I say might, because I wonder how the stacking limits mix with respawn rate: units destroyed in Chungking will respawn a month later, and as stacking rules seem to make sieges last longer, it is possible that at some point, odds ratio never change, because the guys you destroy this month are back the next one.
Overall, I don't think stacking limits change the situation in China. Right now, a commited Japanese player will take all of it, with or without stacking (but it is a lot of work and investment), but that might be because many AFB don't care much for China, and no one has thought hard enough about the counter.
Oh, and about historicity, I'm a bit split about the benefits of stacking. Eliminating the mega-stacks and the big battles at the gate of Mordor is certainly a good thing, but that continuous front line over the mountains and deserts, which just happens once you have stacking, looks very strange (the War of Resistance was a pile of local wars).