Has anyone experimented much with leadpipes on their bass trombones? I've heard good things about the Brass Ark MV50s. I currently play a shires custom with double thayers. Has anyone used one of those leas pipes with a Shires? I've heard good things about the sterling silver version.

As with anything, it depends on the individual. I have used one on my Thayer-ized Bach for several years. I have tried it on my dual-bore Thayer Shires and honestly, I like the Shires#2 better. That said, I know of several professional players who love it on their Shires. (their Shires are single bore) -- IMO, it's worth a try. It's an excellent pipe.

The Brass Ark MV50R (rose brass) is what seems to work really well for me on my Schiller (King clone-ish) bass. It produces a rich sound with easy articulation. But an MV50 from one source will likely not behave precisely as an MV50 from a different source. And of course, the material will make a difference too. The silver MV50 from Brass Ark is a bit too rich for my blood, but at some point I may try the nickel one. Or possibly one from M/K (which offers a trial program).