Concerning the tape application to the HDMI plug, see my post over in this thread: http://www.avsforum.com/t/1419465/wake-from-sleep-issue-edid#post_22380875
With regards to having the HTPC go to sleep, I just decided to allow the PC to be on all the time. I too have a Harmony 700 remote, and I changed the power settings on the Media Center PC device to always have that device on. At first, I was having my PC go to sleep after 30 minutes of inactivity or when I powered things down through the remote. I was having some issues with powering things up and the HTPC come up as well. Changing the order of powering up the devices such that the HTPC was first seemed to help. However, some of my overnight scheduled tasks were also getting interrupted.
I have only had my HTPC up and running for a week. So, I'll have to monitor how this works long term, especially with regard to heat. I have a Silverstone GD05 case. However, since my motherboard only has one chassis header, I ended up plugging the fans directly into the power supply, which caused them to run at full speed. So, ended up replacing them with Antec TrueQuiet fans, which have a switch for Low and High. I could still perceive the fan noise at high. So, right now I am running them on low, which makes them barely audible. Actually, I think the Intel CPU fan is louder. I'm not sure how much heat is too much. Generally, the CPU and GPU idle in the low 40 C area, with the CPU going up to 52 or 53 C when watching TV. The GPU can go up into the low 60 C when watching a MKV movie with madvr. Anyway, the only concerns I have about running the HTPC full time are heat and power usage (we'll have to see the utility bill next month).