I'd love to see them booted from NFA, but don't believe they should be classified as a firearm of any type. I can buy a lawnmower muffler in a blister pack hanging on the rack at the hardware store.... a gun muffler shouldn't be treated differently.
I've always felt that the health angle was the way to go on this. This is one instance where we can use the "they do it this way in Europe" argument to our benefit.
That is my thought as well. Suppressors should just be another accessory no different than a muzzle brake or flash suppressor.