1. Is there a "spare" SATA connector, and what would it take to add an external port ? From your earlier posting I think there's room on the back panel.
2. Cable management - and this has always been a bugbear on the whole iMac range - why not cut a slot in the stand to feed all cables through for neatness ?
3. Have you tested the HDMI input, and what does it look like ? Would you watch TV on this with the addition of a USB tuner ?
4. Let's see it go back together...:-)
Seriously, fantastic teardown. I showed the Mrs and she hit me, yelling NO, NO... go figure...