An A-210 is certainly a different beast than an HTPC and brings both advantages and disadvantages dependent on your needs. It is a much simpler approach to streaming, you turn it on or leave it on and it's ready to go and of course has the remote control. The GUI can be a little frustrating on these boxes, it may be slower than you are used to after an HTPC but once you get used to it and learn to navigate around you should be alright. There are plenty of skins and customizations that you can add in if you ever have the itch to spruce up the display. One thing to make sure about is the audio playback. I don't know how the A-210 handles HD audio, if it bitstreams HD audio or not. As you say you are picky about PQ & SQ so you will want to make sure it handles the audio formats you prefer when watching a movie. Some of these boxes struggle with some of the HD audio formats, that is they will have drop outs and pops, that sort of thing. There are plenty of forum threads devoted to these Popcorn hour boxes and I would read them before investing.
I would investigate other brands of streamers as well. I have a couple of WD SMPs and they work pretty well. Both bitstream HD audio and I have no trouble with high bitrate files playing. Anyway, there are a lot of options to choose from and I understand wanting a simple streaming device. I have both an HTPC and several streaming players and use them all depending on my mood at the time. These things become a hobby, plenty of people on this forum have had a half a dozen or more of these boxes. Every time I see a new one come out I'm tempted to try it. Good luck with whatever box you get.