The original Deore line was intended as a touring group. As mountain bikes became more popular, the touring apect of Deore was kind of lost. I love the look of the M732/M735/MT60 derailleurs. I'm not the most discerning 'period correct' type- but IMO- the look is pretty much the same from 1986-1993. My 1987 Schwinn High Sierra came with the MT60 and the 1987 Voyageur would have had that as OE as well. Again, in my opinion- a rear derailleur from that lineage looks just as comfortable on a tour-ish bike as on a mountain bike.

I'm probably one of the last people you'd want to ask about shift quality- but it seems that that first generation of SIS was hugely successful and saw minimal changes over the course of 6-7 years.

Regarding the Deore XT stuff of that period- the descriptor you'll hear most often used is "bombproof."