Temporary upgrade from 6950 while waiting for Haswell build

[Vanderburg]

So, I was going to put a 3770K build together in the next couple months, but decided to wait for June-ish to put together a Z87 build, since I'll have an opportunity to save a bit longer and put together something nicer with a 4770K.

So, my question is, I'm currently on an 8150 with a 6950 and I periodically play MoH:W, BF3, Skyrim, etc and my performance is so-so. Should I be satisfied with a 7850, or would I be more inclined to pay an extra $50 for a 7870, when it's only going to be for 4-5 months? I don't mind paying the extra $50, but would the difference be that great? If yes, I'll pay it, but if no, I don't see a need.