-which sample formats supports the jjos2?
wav. inst pgms are built inside the mpc, though there are ways to make it a somewhat fast easy process.
-how many samples/keygroups are allowed for a instrument?
technically, 127, though you will never see me with that many samples in an inst pgm! i typically use 28
-crossfading?
none yet, but hopefully in the future. phasing can be an issue w/ crossfades but otherwise it's a really nice way to blend multisamples...
modulation?
ADSR and aftertouch for amp, filter, pitch and LFO.
i think up to 4 layers per note, right?
nah it's not a per-pad basis. you can technically have 20+ layers, however many you want, but they are not triggered velocitatively, ie they all play at the same time. instead, to simulate more gently struck notes, i use velocity to modulate a lowpass filter. also, i love to throw a qlink to track sample start, and use that to go back and edit certain notes that need to have their transients "calmed down."
INST pgms are not more powerful than the vast majority of soft samplers, vsts, etc. however the workflow is very very smooth (AFTER you built the pgm, of course!) so i find myself using inst pgms every time i work with the mpc.
i often use them as sketchpads/layers for future work in Reason/vst. i
'll make a melody and then load a similar patch in Reason and see how they jive together.
last, here are 2 vids regarding inst pgms
part i :
http://www.youtube.com/watch?v=IMWT1blUZjY
part ii:
http://www.youtube.com/watch?v=7BmGLZG4L04
