Well I bought my MSI TF3 PE/OC GTX560ti448 for around $230 when it was on sale at Amazon. (US Dollars)
Not sure how much you paid for your HD7870 but the perfomance seems close with the win going to the HD7870 IMO. Based on pricing the GTX560ti 448 seems like a much better deal though.
My best 3dMark11 score so far is just under 8000.
http://hwbot.org/submission/2259829_sonda5_3dmark11___performance_geforce_gtx_560_ti_448_7954_marks
I've been told by a few over clockers that if I had a 2600k and over clocked it I could probably get another 1,000 points added to my score.
I'm planning on getting an IB cpu ASAP and when I do I am going to run chilled water in my loop. I'm hoping for some scores close to 10,000 on 3dMark11.