Kevin,
Keyboard action? Pass - it's a question of taste. Personally, I use the 76key unweighted versions as I don't like playing organ on fully weighted keys.
Programming? I hear what you are saying about a 'simple mode' - have you tried feeding that back to Kurzweil themselves? I hear nothing but good things about them nowadays when it comes to feedback.
K2500? I have two racks of these and it's important to note that :
- the PC3 is actually balanced outputs
- the PC3 sounds a darn sight fuller than my 2500s
- the PC3 has _more_ effects than the KDFX
- in fact the PC3 has more programmes, setups, zones, quick access banks, arpegiators, etc
- personally, I prefer non-volatile sameple memory to hard disks as the drive is usually there to just push data to the sample ram and the workflow is simpler
- there is a full editor for the PC3 (*)
- there is also USB connectivity for both midi and file access on the PC3
That's a fair few differences!

(*) NB : I started working with the editor and frankly found it more confusing than programming the damn thing directly. I'm no expert, but I can navigate quite quickly around the unit. So much so that I suspect that a larger display would really only show fancier graphics rather than significantly more information.
I'm not saying that the PC3 is perfect - far from it, but it is a helluva lot of bang for buck. The Korgs and Rolands at this price point are, imho, just full of silly gimmicks rather than being genuinely more innovative - hell, the Phantom G series is the first time ever that I've played on a synth and not been able to change patch with a single button click!

Plus .... and this is the killer .... the Kurzweils _sound_ good. Surely that's got to override everything.
The new 'LE' versions of the PC3 leave me cold - more silly gimmicks and my prediction is that they will be complete flops. But this puppy ... I'll bet you a fiver that they start cropping up more and more over the next couple of years.