There is a thread here that I currently can't find that discusses this with actual numbers. For me that difference is OK. We do a lot of long trips and the bigger battery is a must, but if you don't do that or don't live in a very cold area, it's not a s big a need.
It sounds to me like you know exactly what you want/need and that's a 3 second car! What a great present for you! I envy your journey and hope you get back home soon.
I know for a fact that if "I" got a P, I'd be "required" to occasionally (OK, daily) spank unsuspecting BMW's, Mustangs, etc. and at some point it would catch up to me in tickets and insurance rates. I'll stick to the M3 AWD LR with the perf unlock and put the money saved in ceramic paint coats, etc. The places we like to travel still have some super charger holes so even with a CHAdeMO adapter, I need the extra range.