I did it without asking, but I did what's in the title. Went from X360 - PC - PS3 to PC - PS3 - X360. Mostly because PC has lots of runs, and the fastest times are achievable there (not bragging, it is the way it is). PS3, while it doesn't have the second fastest times, has way more runs than X360, and in various difficulties. Coop leaderboards were left untouched.