A sometimes-mentor and someone in the know at a professional orchestra advised me recently on writing for orchestra. I'll paraphrase his advice here:
Writing for a flute player doubling on piccolo reduces the chance of us playing the piece. Even though it's a very common thing to do orchestration-wise, we'll need to hire an additional player for the night because the union rules don't allow one of the flautists to play it. This additional budget could be the difference between us choosing to perform your piece, or not.
He also suggested I write for a Mozart-sized orchestra as I'm getting my name out there. There is likely a classical-era piece on every program and it's a guarantee that they won't dig into their thin margins to program my work. It sounded like good advice to me.
Now here's the question... Do the same union rules hold true for the clarinet parts? I think they would be much nicer to play on an A clarinet instead of a Bb clarinet simply because of the key signature. But it's certainly nothing a pro can't handle. Note that I am not referring to bass clarinet, just the standard A/Bb soprano clarinets.
In case you're interested, the piece is in A. So the key sig would be B major, or C major for A clarinet.