For the record, I'm in a jazz band as the pianist full time (school band), so I have experience playing with other musicians. It's not the same as playing with an orchestra, granted, but it's a whole lot better than nothing.
I've played the Mozart D minor Concerto, and several romantic styled (new age) concertos.
The hardest Chopin? Probably the G minor ballade, yes. And I scared myself with it because I (for the first few years of my piano career) was told that technical difficulty was basically indescribable mysticismic movement. Nobody would tell me what exactly it was, and thus, what I thought was difficult "technically" wasnt.