Hey
I performed the first movement of Mozart's Concerto n. 20 in d minor K.466 in my exam last year, with my teacher playing the orchestral part on a second piano; wonderful experience
This year, I played the full Beethoven Concerto n.3 in c minor Op.37 for a concerto competition. I didn't win it (a singer did...) but I will get to play it once with the orchestra anyway, and I'm really looking forward to that. My teacher told me there's nothing like it

I think the most important thing is, you should really know the orchestral part as well as you know your part
Next year I plan to enter a few concerto competitions, but I'm still hesitating between what concerto I should work on : Shostakovich n.2, Schumann, Brahms n.1 (seems a bit big), or Rachmaninov's Rhapsody on a theme of Paganini, which seems hard but not impossible... Any advice or suggestions of concertos ?
About Music minus one, I tried it with Beethoven n.3 and didn't like the tempos... so it wasnt very useful