He told me that u don't see many cave divers with them on. I took that as if there not on then there's a reason for it
8" doubles, with certain tank boots do have a decent risk of getting a line caught between the tanks and getting hung up. The boots that are octagonal are particularly prone to it as the points can be almost touching and the flat bit above them makes it quite difficult to get out.
The smooth edge tank boots that came/come with Faber tanks eliminate this, but they do like to trap water which can cause corrosion to be accelerated especially since Faber tanks aren't hot dip galvanized.
I agree with no tank boots in an overhead on 8" diameter doubles and believe it is the only situation where there is actually a real risk of entanglement.
With 7.25" tanks there is a 3/4" larger gap between the tanks so any argument about an entanglement hazard is irrelevant in my opinion. Don't see a lot of 7.25" diameter doubles because of size requirements for big dives so most people go straight to tanks like LP104's/108's.
In sidemount it is also irrelevant since the tanks are fully separate.
Is it possible with 7.25" doubles and sidemount bottles to get hung up? Yes, absolutely, but you have to get the tank hung up, then twist around to wrap the line full circle above the tank boot, then try to slide it off the bottom and it will get hung up on the boot. If you do that, I'm sorry, but you deserve to get hung up and stuck there because that is seriously impressive.
A huge part of why you don't see them in cave country is the historical fact that no one had tank boots down there because of the DIR movement making people take them off. Take that 20 years later to now, and basically no one in cave country buys new tanks so there are no boots to go around.
