I just got a set custom made by as set of doctors at Lagun Seca. WOW! I've been wearing plugs for a long time, and these are THE SHIZNIT!
Sure they are a bit more costly (at $45) but they are totally custom fit and SUPER comfortable. I wore them on a 16.5 hour blast from Monterey -> Seattle last week.
They pop in and seat. The doc said they are a rated at 29db. I don't know how they compare to the ones you speak of in that regard but they work far better than ANY generic earplug I've tried yet (I'm also a firearms instructor and I've worn A LOT of different earplugs).
This is the outfit I got them from. Next time you are at a motorsports event try to get some, or contact a local audiologis (sp?) and have some custom made.
The ones I have are washable, and they say they should last about 2 years. Sorry, I'll have to snap some pictures of them later (my camera is dead at the moment)
Upshot is the legal aspect of them. They are medical hearing devices and therefore you are protected from citation (at least in Kalifornica) for wearing them under your helmet. Sorry, I don't have the CVC for that, but they did have it (of course) posted on the booth.
EarPeace is the company. No website on the case but here is the info:
410 Estudillo Ave.
San Leandro, cA 94577