Just because something is new and laden with midi features does not make it "better" than an older device. Both synths sound completely different. The MS-2000 is very digital and stable sounding (analog emulation, my a**). The MS-20 is gritty, dirty, with an unbelievable bandpass filter.
Try patching the various outputs into the external processor for some unpredictable effects. Personally, I would take a MS-20 over the MS-2000 any day...it has a character that is not reproducable on any other device.
Hey, to each their own though...