I cant tell you much as I am using Miui rom and i have killed an M7 a while back but Viper ROm is the best I have used and that is Sense 6. Bare in mind I have not used a Sense 6 rom at all but last Viper i used was 5.5 and it was great.
There is Android Revolution HD, im not sure if this is Sense 6 but is is a custom rom as close to stock that you can get.
Just download the ZIP and enter your receovery and flash, it is simple as. Just dont wipe internal SD card..
O is NOT a Number!
Phones owned: Sagem MC922, Ericsson A2618, Motorola E365, Sony Ericsson Z600, Imate Jam, Nokia 6110 Navigator, Sony Ericsson W980, Sony Ericsson X1i, Sony Ericsson X10i, HTC Desire HD, Nokia N8, Samsung Galaxy Note - whats next?... HTC One (x2 LOL)