Fair enough, and you know more it seems then me with late 90s saracen. However, Acera parts are the lowest shimano do, and whilst the shock may be ok in 1997, the URT design has died a death and you only have to look at the price more "prestige" brands get for their higher URT models, such as Gary Fisher Level Bettys, and Trek Y bikes, to see that the URT 90 suspension bikes just hold little value.
You obviously love the bike, so keep it as it wont make you rich or contribute much to a new bike.
I don't know too much, only what i remember from the extensive research I did at the time (£550 was a LOT of money for me to spend at the time lol) which is why I was hoping to find someone who knows more than me. I agree, acera were low end, only one or 2 above the SIS stuff you got on your bog standard brandless bikes, but with the forks and shock costing so much at the time and with it having a decent frame that was exactly the same as some of the £1000+ bigger boys in the range I guess they had to shave money somewhere (the original Rigida single wall rims and original V brakes could be included in this cost saving too hence why I changed them).
I do love it and always have, so I'll prob get it serviced and put it back into storage and treat myself to someting newer for everyday, just seems a shame to strip it or store it if someone out there would actually have fun using it.