One professional I've played with uses a Cerveny "Arion Baby" F tuba as his "tenor tuba".
I also sense that at times when we talk about the "appropriate" instrument, there's perhaps an underlying dispute between a sense of "historically appropriate" and one of "musically appropriate" -- along with some view as to whether the one necessarily implies the other, and the degree to which each performance should conform to the composer's original desires (based on instruments available to him) or to a conductor's contemporary desires. This mirrors a dispute in certain areas (and "schools") of academic scholarship regarding how much "respect for the text" should be shown in interpreting or making use of a particular author's writings (which may have been created hundreds or thousands of years ago). Such disputes can get very heated and are basically unresolveable because two quite different purposes are in conflict.
A couple of years ago in Vienna I heard a great performance of Mozart's Requiem by Orchestra 1756 using period instruments. But it sounds pretty good on contemporary instruments as well. This isn't to suggest that the trombone solo, if played by a BBb tuba, would be "appropriate" in any sense (musical or historical). There are limits, eh?
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)