The MODX7 is a great value - here's why:
1 - with 76 keys, it's large enough to take advantage of multiple splits, yet lightweight (16 lb)
2 - same software and touchscreen as flagship Montage at LESS THAN half the price
3 - play up to 8 sounds (parts) at the same time, with easy control from the touchscreen
4 - for each part, can can two insert effects, and then a global effect for a combination (called a Performance) - so plenty of effects available
5 - 4 hardware knobs and sliders to control the 8 parts in realtime, plus the "Superknob" that can control multiple parameters at once with one knob
The only reason to get the Montage over the MODX would be perhaps the steel housing rather than plastic, plus instant access to all 8 sliders and knobs (rather than have to switch to using either 1-4 or 5-8). Montage also has a better keybed. But these compromises seem pretty small compared to the price break you get with the MODX