On second thought I think I'll hold off getting the PSR-S950. At least for now anyway. After further examination of the PA600 I think I'll wait until I play the Korg to see if the key action is better than the S950. I already know the Drum kits are better on the PA600. What is also interesting is the PA600 has a larger LCD screen w/ touch control and it's a higher resolution than the Yammie i.e. 800 x 480 vs. Yammie's 320 x 240. The PA600 also has 1/4" inputs whilst the Yammie is a single 1/8" auxiliary in.
One thing I've yet to determine is whether the Korg has an Octave up down feature. It doesn't mention whether it has the feature on Korg's website. The S950 of course does have octave up/down buttons. I haven't been able to find any close-up high resolution photos of the PA600 on the net yet. Using Picasa I can zoom in and see that the PA600 does have two sets of buttons on the right side that display "- +" next to them. Why Korg doesn't list it in the specifications suggests it may not have an octave function. But the two sets of two buttons on the right side of the PA600 may suggest otherwise. Although I can't make out what the words above the "- +" buttons say on the right side of the keyboard.

I guess I'll have to wait until the PA600 shows up in stores to find out for sure. Unless somebody here already knows the answer.
The PA600 is about a pound lighter than the S950 and it isn't as 'deep' as the S950, suggesting an easier to reach, more convenient layout on the front panel of the PA600. The PA600 also has a larger user memory capacity and I'm guessing the Sequencer also allows greater data allowances while recording songs. The PA600 allows up to 100,000 events but Yamaha doesn't list the song recording event allowances for the S950. Although if past PSR models are any indication then the Korg probably blows the Yammie out of the water in that regard. Perhaps the S950 user manual lists the recording event allowances. Although a person can't download user manuals from Yamaha's website anymore unless they've signed up with Yamaha on their website. How ridiculous is that? They not only want your money they want your personal information as well!
All the best, Mike