I used Team OSE's rom on my g2 vs980 for a long time, they do good work.
While browsing around drdevs I noticed they had a folder with official builds for the HTC M8. I thought I'd give it a shot, worst case is I'll just restore something else if this doesn't boot.
Flashing now, will report back with results.
Just so you know, OSE is an aosp rom so it will require a 4.4.4 Gapps package to flash along side it.
Download link is http://www.drdevs.com/devs/teamose/OSE/Official/m8/