I have an '87 240 DL wagon & last year got a '97 850 (non turbo) wagon, & was delighted. There have been growing pains & bumps & bruises, but I still think it is costing me less. I sometimes wish for a turbo, but it is still not ot be compared with the 240 for quickness. Some other differences:
rear visiblity much less with 850, I still have trouble parking (wheel base also contributes)
turning radius much wider with 850, cause of FWD (can't make quick U-ees, all K's)
AC much colder with 850, (but you get to worry about evap going bad)
wagon space looks smaller but is really big (it's wider, & folding of seats is more updated [front passenger folds!]
car is lower, you might bump your head
much more sports car feel
'97 supposed to have the bugs out
must have Volvo specialist mechanic
Unless you have your 240 in super shape (which it may not be cause you're inquiring about a change) the 850 is the great upgrade
There's so much info is on this site, it's hard to go wrong
PS I don't want to keep my 240, and I don't want to sell it. Any advice?
Have Fun