I double on trumpet and slide trombone on a lot of gigs. I use Bach 5C's on my MF horns and a Bach 11C on my yamaha bone. Both mp's are comfortable for me to switch back and forth. I also play euphonium on a Denis Wick, but a switch to trumpet is tougher due to the larger size of the Wick. (But that is the best mp for me and that horn, and I don't usually double on Trpt/Euph anyway)
It took some practice, but switching is pretty easy for me now. It's just a matter of focusing in on what's coming out of the horn. It's mental: If you have a trumpet in your hand - you're a trumpet player. If you have a trombone in your hand - you're a loser. :lol JUST KIDDING!
Sometimes, when my trumpet chops are beat up, the bone does help to rejuvinate them. However, If I play bone on several tunes in a row, switching back to trumpet is a little more difficult. My lip seems to swell a little (which can be tough because I have fat lips to begin with). On the up side. My range on trombone is great. (I wish my upper register on trumpet was as easy as my bone's.) But, then - I wish my trombone facility was as "good" as my trumpet's. :o