in your case you didn't even opted to have a margin at all, since ION is border-line able to play 1080p.
About 30% GPU load and 10% CPU load while playing a 40Mbit h264 1080p stream (google killasampla) is borderline?
if you've thought about it for a sec there a SNB G530+ITX mobo+GT520 would've costed you about the same with a huge margin for improvement.
When I was buying my Revo 3610 Sandy Bridge was the talk of the future, s1156 was just becoming mainstream and nobody was even thinking about 10-bit encoding. I was considering a Core2Duo setup, but it would've been quite expensive. I almost bought a Zotac 9300ITX board, but then found a used Acer Revo 3610 with warranty for the price of the board alone and didn't think twice.
if you're gonna argue about power consumption against this setup i've mentioned then you aren't looking at reviews carefully.
I am, I'm even writing some of them

ION is still unbeatable when it comes to power consumption, so far only the Arctic MC001 (Atom D525 + Radeon 5430) comes close (34W tops when running a heavy game benchmark).
and if you'll argue about the noise this'll give off then you aren't looking at the market carefully, theres a whole variety of passive GT520, and the G530 can be passively cooled as well.
Yeah, noise isn't a problem. In fact, it's easier to keep a G530 quiet than a nettop, where you're stuck with whatever the manufacturer invented (at least without nasty hackjobs).
well thats what i think anyway.
As I wrote above, the situation now is kinda different. When I was buying my box it was all about 8-bit, so focusing on GPU decoding was very reasonable. And it still is, I think, if the focus isn't anime alone. Non-anime stuff is and will be 8-bit for a long time (because STBs, TVs and standalone players support it), so for someone who doesn't watch too much anime, it isn't a problem.
Edit: oh and expect the up coming new profile or format to not be supported by current and/or old hardwares, what was it again? H.625?
By the time it becomes mainstream, I will buy new hardware and the Revo will become a seedbox (if it still works)

I don't expect it to be quite some time, though, a lot of money was invested into h264-compatible hardware (not only on the receiver end, H264 4:2:2 is just now appearing in broadcast encoders), so I don't expect a successor anytime soon.