About 10 years ago, I needed training at SimCom and 250 multi PIC to be insurable in a 340 (and 421). I had about 1000TT at the time. It was a big step from trainer twins - especially if you don't want to turn the owner's engines into junk.

I made $300/day doing it. It was a blast, but it certainly demanded more of me than any turboprop and especially any jet (on a single pilot basis, that is).