There isn't much difference between XC Pro vs. Comp. Both are lovely, cold forged stuff. Limited factory info, best source is to have a period catalog.
Comp rear mechs are even lighter due to having "normal pulleys" not cartride bearing ones. 56 BCD grannies are a real PITA, WTF were they thinkin'?! NOS/nice GG BB-s are rare, (non-GG cartridge ones even rarer) the alloy cups crack easily, they are not for hard use I suppose.
There were 3 different standards for cassettes, some are interchangeable, but not all of them. The freewheel' splines look similar to me though. Thumbies, mechs, cranks, front hubs, champagne coloured brakes/levers, pedals are worth it, rest of the stuff is at least quirky, but not top notch. Seatpost is a quality item, strong, but heavy and short, in limited stupid sizes. Headsets are light, easy to scratch. Seatpost QRs are prone to crack, since housing is alloy, lighter than Shimano though.
Very hard to collect a nice/NOS full set, as availability was rather bad even then, and they went bust shortly after. If you find a good fulll (ish) set, just go for it, even it's pricey, the savings in time/postage etc. are tremendous. I've been collecting Japanese Suntour MTB parts for over 10 years now, quite exhausting, I'm tellin' ya.
One more thing: XC Pro/Comp NOS stuff is almost too nice to be put on bikes built to ride. Well, probably the usually too long search for them makes me to write this bold statement
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