Philbo

I'm no "helmet expert"...(Fnaar)...but unless you're Skelator the flesh on your face will allow some movement. As long as it's good and snug, and your head doesn't rattle about inside you're OK. Just pick something you're comfortable with, and you're already doing the correct thing by talking to the staff. The cheaper lids are more likely to suffer from pads softening up, but you pay your money you take your chance! Just don't confuse difficulty getting the lid on with a snug fit as I did with my old Roof...which is a bit on the loose side now, but still bloody tight to get on.

Good luck with the DAS and welcome to the site!
Phil