For the basic facts and a very credible review for just about any ski made in the past few years, your first stop should always be: www.techsupportforskiers.com
This is a great place to start because the info is in a condensed, easy to find format. Support Peter's service, pay the $20 to become a "member", and you get access to much more info on his site.
Second stop: The PR is probably the 2nd most discussed fat ski (after the Explosiv). There is also a reasonable (but not huge) body of discussion pertaining to the im85. Do searches here and over on powdermag.com to find this material, THEN ask questions based on what you have found. Most people want to be helpful, but really don't like to be effectively asked to re-write what they have already written. You'll get much better, in-depth answers if you build on previous discussions. Its really not that hard to find.
Finally, here's a quick summary to start you off:
These are *very* different skis. Its somewhat surprising even to be asked to compare them.
PR = moderate flex underfoot, soft tip and tail, low swing wt., a bit wider.
im85 = firm flex everywhere, relatively high swing wt., er ...85 mm underfoot.
PR: Good for lighter folks in untracked, light powder; gets kicked around in serious crud. Low swing wt makes it also useful for avg wt people in trees, and at lower speeds in general. Almost no tendency to tip dive in bottomless.
85: Fairly stiff and heavy. Not overly turny in soft snow. Good for the 180+ lb set who go fast and make big turns through junky snow. One of the better 80-85 crud skis for big guys. Not as lively as the Rex, and from what I hear, not quite as stable/burly as the g4. (For the record, I own both 10ex's and G4's, but not the im85.) Also works in true powder, but if this is your primary goal, don't stop in the 80's - go fatter.
Tom / PM[ September 11, 2003, 08:58 PM: Message edited by: PhysicsMan ]