Warren,

Playing trumpet is alwyas more desireable than just working on it, IMHO.

FWIW, however, I do think learning how to lip buzz as close to the way you play as possible has merit, but it does take patience.  I wouldn't  spend more than 10 minutes a day on that right now.  Include lots of lip fluttering to keep them from becoming spent during this part of your warm up.  It might take quite a long time to master lip buzzing and applying it to the horn.  It did for me.  When I first tried it I abandoned it as nonsense after a few weeks.  Then I hooked up with Bobby Shew.  After trying it again at his suggestion I got the hang of it.  I just needed to rest more and not overdo the buzzing and I needed to persist in the learning process.

Just some thoughts.

N Drozdoff
http://www.drozdoff.com