What do you gain - 14 bit midi on the jog wheels, pitch fader, larger jog wheels
What do you lose - some buttons, particularly less transport buttons (2 on the VCI-300 vs 4 on the VCI-100), some knobs
I have both a VCI-300 and a VCI-100, the main thing that cheezes me off about the VCI-300 is the lack of transport buttons, thats a real killer IMHO - i am so used to the 4 transport buttons on my VCI-100 (and to be honest i even think 4 transport buttons is not enough, id like 6)