Using EW Gold here.
Does anyone have any tips for making trombone slides sound more convincing?
Also, is it ~valid~ to do "lip ups" ... that's all I can think to call them, being an X trumpet player ... on trumpet, and also oboe, clarinet, flute?
By "lip ups" do you mean sort of "grace bends"? If so, they work well on the clarinet (which can actually do long glissandos and so on... but not just ANY note to ANY note!) and you can bend many notes of the flute, but not by much. If you're writing these for live players, make sure the players are practiced with these tricks. They aren't especially hard, but some people never try them. You'll hear bends in "jazzy" clarinet solos, and sometimes in flute as well.
Oboes have a few bends available, but it's not that great or useful. I've only ever written them once when they are bending along with everything else, and even then the player may not be able to do it, and might just substitute a grace note. I'm no oboe player, but I'm guessing that since it's hard enough just to play an oboe in tune at all, controlling bends must be difficult. I could be wrong though, maybe some people can go to town with it. But I've never heard it.
I met one bassoonist who claimed bends were impractical, then a week later I had a guy over who was bending all over the place, and very accurately. Maybe a bassoonist here can chime in on this... I'm afraid to write bends for bassoon until I better understand them... I've noticed bassoons are more varied in construction than other instruments, and this could have an effect on the practicality.
I would reccomend getting together with a good player on each instruments, and, preferably one familiar with both "jazz" and "classical", and getting a first-hand demonstration of what they can do. Bring a tape recorder! You want all of that info for reference.
Sorry if this was completely unrelated to your question!