Single threaded worse than a G850. ouch. At least multi-threaded keeps up with i3.
Xbit was able to match discrete 6670 performance by overclocking the CPU, RAM and iGPU.....of course ddr2400 costs double 1866 .
i3/ GT440 or HD6670 I'd guess to be ~15+% faster and slightly more expensive. Typical HTPC cases don't seem to offer much in the way of dGPU ventilation, or at least mine doesn't. That could result in a noisy system with the smallish fans that the budget cards often come with.
The faster, unlocked APUs cost the same as the 65W versions. Downclocking and undervolting the K's should get to 65W.
Edit: picking through the benchmarks, it looks like the i3 doesn't really spread the dGPU gap much without a high end card. 10% with a HD5830 at Anand and 20% with a GTX680 at xbit. A lower end card may be closer.