The “specter” model is even small enough to fit under some (very large diameter) tubes and rails. The downside is higher cost and, well, it’s two parts so it’s probably weaker and less secure.
If I were stuck in a ban state I would be most inclined to get a crowned, unthreaded barrel and have the last inch machined to whatever I wanted and was legal, like Magnaporting, etc.
Adams Arms did create a wreduced radius flash hider, they use it on their 14.5" builds as do we on our 14.5" rifle. They nick named it the manimal flash hider as the machinist who made it has that nickname. I was initially interested in the diameter and how much material was present, machined, etc. In testing the product I’ve been impressed and it works like it should, of course the main benefit being you can remove the gas block.
I did some basic testing with a camera on manual exposure with this FH and a standard a2. In my unscientific testing the flash signature was similar in brightness and pretty comparable, different shape slightly best way to describe it. I was using a cheap point and shoot camera and the photos were pretty crappy in quality so once I have some nicer equipment I think I can get a more accurate result. I have a friend who is a photographer and we are planning a night shoot with both video and some high resolution stills to show the differences. Once we get some quality images I’ll post a video or photos of the two locked on a manual exposure. I’ve also been looking to see if there is a reasonably priced option to do some slow motion video but I’m still looking into that.