OK, I've read a few threads about Doubling on Tuba. I'm pretty Tuba dumb, but I know a few things, like there are different sizes - F, Eb, CC, BBb. I'm a euph player these days. Moved from being mostly a bass bone player. So please chime in on some equipment questions:

1. What size/brand tuba do you doublers play? I'm thinking of both concert band and brass quintet playing. Adams makes a doubler's euphonium. Does any brand make a doubler's tuba?
2. What size mouthpiece? I play a Wick 4AL on euph. I've seen where doublers use a Wick 3?
3. Doublers want a decent instrument - not a student model, nor a pro model. Any suggestions?

Thanks!