Yeah I would definitely skip the 6870 as it was actually slower than the 5870, the 6950 2GB and the 6970 would be the more logical step up IMHO especially if you plan to do Eyefinity at some point.
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--John
i5-2500k@4.8ghz, Asus P8Z68-V Pro/Gen3, 8GB G.Skill@1600, Noctua D14, X-Fi TitaniumHD
MSI 560Ti/448OC 1280MB@900/1800/2250, 3 x P2310H monitors, HAF932, Corsair TX850, Win7x64Pro
TrackIR4, Saitek X52Pro + Pro Rudders + Cessna Trim Wheel (sim flying)
Fanatec GT2 + G27 pedals (sim racing)
PSN/XBL/Steam/EA/ProjectCARS: Kludger
iRacing/rFactor2: Joao Silva