I've driven at this point EVERY version of the Tesla, except for the new 70D. I've put at least a few hundred miles on each version (except for the P85+ which I did only drive for about a day). But I had the pleasure of a small round trip in the P85 loaner I had one weekend. I now have an 85D daily driver, and have put a few thousand miles on it already. That being said....
Handling/Suspension - Without a doubt the RWD fun of the P85 is missing from the 85D. You get more throttle controlled enjoyment from the P85, and it reminds you that it is a heavy but still rear driven car when driven hard. Comparatively, the 85D feels very stable, perhaps a bit less squirmy when the suspension is unsettled, but it is indeed less "fun" if that is your goal. Would I say it is less fun in a negative way? No. I happen to prefer AWD cars because of the optimal handing, but also living in the snow belt here in Ohio.
Power feels VERY similar-- the P85+ that I drove recently was on the latest software and I recall feeling as though it was identical to my latest version 4.4-second 85D. I guess if you really juice it off the line you have the traction issue to deal with, though I always felt the RWD Tesla models made GREAT use of their traction. Acceleration feels very much similar.
Both cars are going to feel similar in weight, have the same pros/cons of air suspension I suppose, etc. IMO the air suspension + 21" combo is the best for handling. Though I prefer 20s on my car, which is what I'm running. I still like the air, but more so due to Ohio roads. Lowering the factory steel suspension by adding alternate C-clip locations worked nicely, and gave my 85-RWD a lower center of gravity.
What are you hoping to learn from others experiences? Are you cross shopping both options? I think the 85D is the better buy, for all conditions, better acceleration around corners (higher exit speed) etc. The only reason I'd personally ever consider a used P85 over a new 85D would be price, or being a RWD lover. And even then I'd urge the 85D, personally.
EDIT- just saw you have a P85 now... so maybe you're considering an 85D upgrade? Either way, I'm a huge fan of the more neutral handing (less rear bias) of the 85D. But that is def personal preference and not a "better vs worse" characteristic..