Thanks for the pointers, everyone. They ended up just laying down scratch tracks just to finalize individual lines and phrasing, which they did together, so I just threw up an SM57 on each, which kept them fairly isolated and therefore easy to differentiate for nit picking harmonies. The trumpet sounded way too thin (requiring a substantial amount of low mids to bring back some tone), sax wasn't bad, a bit flat and lacking that emotional detail like breathiness and keying noise; trombone sounded fine to me.
The Milab is a high quality mic, and I was suprised no one suggested it for any one application. The e604 suggestion got me thinking - I have read somewhere that it shares the same capsule as the highly regarded MD421. The C1000 does get a bad rap, but I've had good results with steel guitar, prefering it to the way more costly Milab in that instance. The M88 I was considering for sax based on something I'd read, but it does seem to me that a condenser mic is really the tool for the job if I'm to capture the instrument in its entirety.
These guys are very good players, especially the sax, so am doing my damnest to present them with a good recording. So far so good with the drums, bass and keys, so I'm halfway there.
Thanks again for all the suggestions; with so many options, it was a bit daunting, but your replies have given me a bit of focus to go with.
Cheers,
Robin.