85 owner here, since july 2015.
I've had several P loaners, including P90D Ludicrous. No P100D so far, admittedly.
Though in the first year, like some others, I would stay away from punching P loaners, being afraid of feeling sad to own a 85, I lately changed my mind, mostly for doing some launch for the kids.
Surprisingly, though the perf is for sure better, it made me appreciate my 85 even more. Because, damn, my car is fast.
If you have a family, you'll soon notice that those acceleration bursts that Tesla cars offer at any speed (and even more so for a P100D), are fun at first, for passengers are really getting sick quickly. Hence the Chill mode btw.
The only reason I'd go for a P is if cash did not matter. But that's just me.
Anyway, you won't regret your choice, any Tesla is a grin inducing device