my take on this ---
If you want to do this like...now --you are already used to crop sensor going with a 7d isn't like stepping down. Its a good body with many strong features. The mk2 does have great IQ and will be better at higher ISO than the 7d. Its a hard choice. I just upgraded to the mk3, and my 7d is now collecting dust and I am not sure what to do with it (keep it as backup, sell it and snag a mk2 as backup, or wait till the 7dmk2 or the new entry FF comes out)
Advantages to 7d - price, range, AF
Advantages to mk2 - better overall IQ, better at higher ISO's.
how quickly are you thinking? If this is something you want like within the next month, the option of waiting for the new entry FF isn't really there because its doubtful it will be available for a while (my guess would be late fall, just in time for the holidays, but, they may wait till 2013 to roll that thing out too...who knows)...
So if you are thinking now, its between the 5dmk2 and 7d... and thats tough. I know the mk2 is great, but, on the times I have used it the feel of it never wowed me. I know the 7d quite well and it is a damn good camera for the price. Good side is prices are coming down on the mk2...if you can find one used for $1500, do it! If not, i wouldn't drop 2k on it now.
Now if you at all want to wait for the new ff...id say save up...and once you hit 2k...keep saving. Ya never know, by the time that ff comes out, you may have enough for the mk3! Which I can definitely say has wow'ed me!!!!