Spoken language interpreters would so much rather work from their second language to their first. It makes perfect sense.
Sign language interpreters rarely want to work from sign to voice. That also makes perfect sense, in a non-sensical way. From my perspective, when you stand in front of an audience of one and you are signing away who knows if you are making full sentences or even delivering the message. Perhaps the deaf consumer does, but how often does a deaf consumer actually go up to an interpreter and say "Hmmm, I understood about half of what you signed."
But if you are voicing...it's hard to cover up those awkward silent moments or those sentences that just trail off.
To be an interpreter, you should be a fairly balanced bilingual. At any rate, you shouldn't feel like you can go out there and sign your heart out knowing that if the deaf person really wanted to express himself that you'd be flummoxed.
Also, don't show up at assignments, look at me and breathe a sigh of relief-- Oh great you are here, YOU can voice! I'm pretty sure we are getting the same hourly rate.
As far as I am concerned you are only as good as your weakest skill.
I'm not putting down those interpreters who are still striving for greatness. Whether or not they reach greatness isn't even the point. It's about the drive and the knowledge that there is still more to achieve.
It's okay to have more to learn. It's just not okay to believe you've "arrived" before you actually have.