Well, a drawback is seldom promoted as a 'feature'.
With any luck, and if the Korg forum posts reflect anything we say here, perhaps Korg are ready to address some of it's main issues?
Me, I can't see how adding a few more fills is going to tax the OS much... Most arrangers went from two fills to four or more with nary a hiccup. Years ago...
The main thing Korg needs to do PRONTO is bring out a new PA3 with tons of samples recorded specifically for the DNC engine. That's the ONLY thing that prevents it from sounding and playing as well as a Yamaha. But you can't make articulated samples out of non-articulated recordings. They HAVE to be recorded specifically for the feature (at least, acoustic instruments do) and Korg have lagged badly after introducing the feature, but stopping short of completing it.
These two things could easily make the next PA a serious contender against the TOTL Tyros's.
Add in a revamp of the folder structure, and you've got a winner. Add in some Karma, and you've got total dominance!