Andrew Lloyd Weber Requiem - Tuba or bass bone?

[MartyNeilan]

I was recently handed the bottom low brass book for the Andrew Lloyd Weber Requiem. Most of the parts say Trombone IV, and a few even seem to have "Tuba" crossed out and trombone 4 written over it. However, almost the entire Requiem is in the pedal register for a bass trombone. I am thinking that, given the range and style (I don't know how much grit and growl would be appropriate for a Requiem) this would work far better on contrabass tuba.
Any TubeNetters ever play this piece?
Disclaimer:
This is a college/ community orchestra and they probably won't really care which instrument I play as long as it sounds good; I am normally asked to play tuba with that ensemble.

[MartyNeilan]

The big CC worked well and blended nicely for all movements at the performance last night. Just had to use the small mouthpiece to tighten / brighten and to be aware to keep a lid on the volume. The "march" section definitely sounded better on a tuba than it would have in the basement of a trombone. Even got to use my homemade 5/6-6/4 mute for 2 notes! (actually 4 notes, because of a repeat!!) I kept my gigbag next to me, turned inside out, to "catch" the mute in the 2-3 measures I had to pull it and start playing again. The performance was in a very live cathedral and a dropped mute would make quite a racket. The acoustics were absolutely marvelous for the medium sized choir - they really don't build 'em like they used to!