Two nights ago I went out with this setup ...
Patrol on left eye, 14 and COTI on right eye. 14 and coti enable targeting of critters with paq-4c on carbine.
The Patrol was for longer distance (hands free) scanning. I was mostly rolling on 4-wheeler hence needed both hands to operate.
For about the first half of the perimeter check, I had the patrol on 1x ... for the second half I left it on 2x ... because the patrol was on my left eye and I am right eye dominant, I could sort of turn the patrol on or off with my brain or worst case by closing my left eye.
I don't see the weight being an issue, Per TEO web sight the 35mm REAP2 is 20.8 oz ... I just weighed my patrol at 18 oz even. Just add another 2-3 oz of counterweight to the back of your helmet and you will be fine. The COTI I had on the 14 weight 5 oz.
But, the extra magnification could be an issue if you want to move while the REAP2 is up there. I was fine rolling at 2x digital, but trying to merge the 2x image of the patrol and the 1x image of the 14+29 obviously isn't going to work very well. The patrol image was VERY clear that night ... and I didn't need the 14+29 except for shooting. Can't see the paq-4c ir-laser without the 14 ... and the 29 means I could see the critter even if it was in the woods.
So, I definitely think using REAP2 on head is do-able ... but be careful when moving ... until you get used to it. And if moving in dangerous ground (where you might fall of the side of a hill) ... I would switch to a 14.