I've pondered this. But never dedicated the time to actually looking into it.
My feeling is I'd want a user-serviceable can, and I'd run powder coated bullets. If you had that I think you'd be covered both subsonic, and, with the correct alloy, running them hard (anywhere up to 2000fps.).
I've never powder coated, just always cast and lubed, but it seems like powder coating would help cut down on the mess with both lead and lube flying out the end of the barrel. You can clean the lube and carbon fouling out of a sealed can, but lead would be a different story.
I've been thinking about it in terms of a .45 Suppressor that can run from .45 ACP to .45-70 (along with .45 Colt, .450 Bushmaster, .458 SOCOM, .458 American), and again, be user serviceable.
Hope mentioning another forum isn't against the rules, but I'd look over on castboolits and see what those boys say about it. Most of what I learned about casting I learned over there.