tubashaman wrote:Would a F tuba maybe take less energy out of me and allow me to do more musical things
Perhaps I read more or less into your post than you meant, but here's my thoughts:
I didn't read that you were considering an F for Sunday, nor should you.
If the program you chose is a bit much for you, consider what you can do do make it easier on your chops NOW. Go slow. Rest up. Talk to the audience. And learn from the way you programmed this time. Another mouthpiece will be VERY hard to pull off, unless you are SO comfortable with it that there will be
NO note, response, or intonation issues.
If I wasn't 100% sure this close to a performance, I'd do less, not extra, to conserve what you can put into it.
As far as how you will react to an F, it wholly depends on the mouthpiece, horn, and what you put into it.
I, for example, have a 6/4 F that I play with my regular equipment, so no, that's not any easier, just more secure up high.
A small F or Eb is with a smaller mouthpiece is entirely different. To get a feel for which direction you may want to go for solos, toot a little on a euphonium. They should be readily available anywhere, and will give you a taste for what a smaller horn will do for you. Whether or not this is a way you want to go will be entirely up to you.