Sorry just seen your reply and not much I can do to help I'm afraid. I know the pain about W7MC being derelict, I was hoping for great things with W8MC and nothing came.
One possible workaround would be to not set the HTPC to sleep when it's idle (since, for me, Remote Potato won't work when it's sleeping) and, instead get it to go to sleep at a fixed time, wake up at a fixed time (using a scheduled task) and then immediately reboot.
In my set-up, I have a task that runs at midnight which checks if nothing is recording and, if not, puts the computer to sleep. I then have a scheduled task that runs at 7am in the morning (so forcing the computer to wake up), waits 10 seconds and (if nothing is recording) reboots. I'm happy to share the scripts with you if you want, but I'm pretty sure you can work it out yourself.
This isn't quite as power efficient as your current set-up but ... the handshake issue will go, you'll have a stable platform (since W7MC seems to need a reboot to run okay) and you'll still have 6 hours (25% of the time) where the box is drawing very low power.
Might be better than nothing?