I would never recommend a sandy bridge I3. No overclocking, and it's only 2.5ghz.
I have that I3 550 in my mini ITX build at 4.0ghz 1.2625v, I'd put it against even the regular 3.1ghz I3 2100 anyday and it will beat it in everything as far as speed is concerned. And it still runs cool, 40c idle and 75c load on the stock cooler. That may sound warm, but bear in mind this is a mini ITX build, everything is crushed in there with no air circulation so those temps are very good. Also thats prime 95, the most that happens on the HTPC is watching a movie which uses ~5% of the CPU so temps never ever go over 50c anyway with normal usage.
As far as power consumption...who cares really.