I think the reason the tenors went to treble was to make it easier for people to change instruments without reading issues, the exception being the bass bone which was in G and too much trouble so stayed in bass. I have come across treble bass bone parts - mental with the ledger lines!
There seems to be a bit of a stooshie about Bb pitch treble for trombone. I played the acrobat many moons ago at school and read the bass side but as been mentioned already the treble side is exactly the same as it was written by a brass band oriented composer and is much loved over here.
I've got a few bass bone pieces where on the other side you get a treble clef saxhorn part which isn't in Bb. You can also buy a lot of the trombone concertos in both bass and treble over here for the brass band players, there's even a brass band degree course in Manchester.
If you think this is all confusing try this.... a lot of the band music I order for school band now come with "world parts" where you get Bb bass clef for trombone/euph/tuba plus a couple of other weird things which are for European bands.
Ross
Likewise in all my years in a brass band I never saw a valve trombone. In fact I don't think I have ever seen a valve trombone in the flesh.
In our band some of the older tenor parts were in tenor clef. That used to cause all sorts of confusion for conductors who were "brass band only".

I've never heard of bands that use transposing bass clef.
Ronnie