... If you want to bridge a pvs14 to a thermal and flip one or the other up out of the way to have both options then that's fine but trying to use both at the same time to create a "fusion" just don't work for most people ...
I'm one of those NOT "most people
I've been running thermal and nv on head since late 2015. Yes, even when I proposed to run Armasight Q-14 (pre FLIR version of the Breach) or the Patrol (I had both) on my head, I was told "you will fall over and die".
So for the first few nights, I stayed close to the house, to make it easier for my wife to find my body. But I didn't fall over and die. In fact (knock knock) while I've had a few bad falls in the day time doing farm work, I've not yet fallen at night. Moving slower, more carefully maybe.
With a q-14 or patrol or skeet or breach or odin gen01 up on my head with a 14, the images don't fuze. I.E. they don't line up. Its like seeing double. But I've been seeing double all my life so it doesn't bother me. Somehow my brain automatically selects one or the other image to see - most of the time - sometimes it sees both. But its not bothered. IDK why not.
I also run various cotis up there with the 14. Depending on what I'm doing.
I use all three of these setups.
From left to right
14 plus ce-coti (640) often on a night cap. Its lightest and handiest - If I wanna move fast. And on most nights I actually like having the extra FOV of the unaided eye ... and yes an unaided eye can often see a useful amount of terrain etc out there. The 640 thermal gives PID out to 150yds and supports shooting with the laser.
dual 14s with coti. I use this when driving or otherwise doing something that benefits from having depth of field. But I still have the thermal up there for shooting with the laser. The 14 and coti images do fuze, so I hit what I'm aiming at with a coti+14.
Nox18 with 14+coti.
This is the heaviest setup but provides longer distance scanning with the n18 and still provides fuzed image with the 14+coti for shooting with laser.
I've still never tried dual thermals, but that would rule out shooting with the laser and I like having that as an option when "walking and stalking" at night. If I'm setup on a tripod with a rifle. Then don't shoot with laser. But if walking and stalking - usually in or near the woods, then I often shoot with the laser, its fast.
I find I don't need to flip up if using config #3 above (N18 with 14+coti) my eyes automatically select one or the other image as primary, even though both are still there. If I'm rolling on 4 wheeler thru a dangerous area, I can use my eyelids, to make sure I know which image I am looking at - and I do - do that on occasion - for safety reason. But my eyelids work well and I don't need to physically flip either optic.
For almost exactly a decade now, I've been told I'm doing it all wrong
But it works for me and having a thermal on my head is very liberating vs carrying thermal in pocket. I can use the thermal whenever I want - I don't have to wait to take it out of my pocket - and I don't need to use any hands - its hands free. Its just up there waiting for me to use it !!
I have heard from many people that they don't like having thermal and NV on their heads at the same time. So I agree that warning the OP that it might not work for him is appropriate and I give that same warning to anyone who asks me. But I also toss in my experience that for whatever reason, it works great for me.