MPC X USB MIDI and Timing

I am on the fence deciding on whether to go for the MPC X or not. I was spoiled with the MPC4000 because it was so easy for me to get my ideas out the way I like and quickly. Because of this, I have been hesitant to join the software world because whenever I would try it out, issues like latency, drivers, compatibility, maneuvering, etc. would send me back running to the 4k. I did get the MPC Ren and I am sort of cool with it, but the timing thing is killing my vibe. I had the 5k and sold that because that was the first place that I noticed it. Its almost like the notes are being forced to some quantization through a software process out of the control of the user. My question is for anyone who has used the 4k and the X, is the timing feel of the X different from the 4k? I do plan on going to a music store and playing it myself but I would like to know if anyone has any thoughts on this.

Secondly, I have read that the USB ports support controllers. Are USB compliant sound modules\keyboards like the Kronos or Integra 7 supported through the USB ports through USB MIDI? Thank you in advance for any insight.

No one has really played with the 'X'.. Those machines are nowhere to be found.. Only at music gear events.. Still waiting for mine..