butr seriously, I think it will cause some hobbyist to be leary of your services.

I have never met a provider with braces, but my ex had braces when I met her and we dated (and had the best sex of our relationship naturally) and the fact that she had braces was not an issue as far as BJ's went, amazingly enough.

In my case the BBBJ was super and the braces were not a factor at all.  As already mentioned, with or without braces, BJ's and teeth do not mix well at least in terms of a biting action.  However let's keep in mind that the bottom edges of the teeth are not covered by braces so this fear is essentially moot anyway.  Sliding the tip or shaft across the outter teeth surface can be erotic at times and this would certainly not be an advisable move when weraing braces.  I would also think that if any elastic bands were present (they were not in my case) then that could become an impedence.
   
At the end of the day the dominant action involved in BJ's are wet slurping and sucking using lips and mouth while the teeth are safely retracted away.  A skilled lady will have no problem delivering superb BJ's weraing braces.
However I think it is fair to expect that some guys may get freaked or turned-off.  In my case the young lady was extremely attractive and her braces did nothing to erase the fact that I was enjoying the company of a gorgeous woman.  I will admit that I was probably initially more hestiant about DFK's than I was about the BJ.  But that too quickly passed once the games began.

Truth be told my guess is that you will find guys put off by it, guys who could care less and guys who may be hesitant at first but will quickly come to see that it is no big deal.  Good luck.  I'm not a dentist nor do I play one on TV but the advantages of getting this done and behind you are well worth it in the long run with regard to an improved smile and proper teeth, jaw and biting alignment.