Respectfully disagree with the above, I think UWorld was fantastic for C/P, and the main reason I got a 132 in that section. I'd say get both if it's only $100 extra - FLs for timing, and UWorld for reasoning practice/content review check. If I had to pick one though, I'd go with UWorld (plus all AAMC tests of course). How much time do you have before your official test?