My honest answer to the question is: I don't know. My business (automobile dealership) is such that nearly all employees are responsible for face-to-face interaction with the customer, with the exception of the staff in the back office (accounting and such). Would I hire a TS for a sales position? I wish I could say yes, but I really don't know. I have had a couple of openly gay and lesbian salespeople, all who have been excellent, but without exception you wouldn't have picked that person out of the crowd and said "yes, he's gay". I do have two lesbian mechanics who are clearly of the more "butch" type, and I wouldn't be surprised if one of them eventually transitions.
As a company we are also committed to diversity, I can honestly say that we are well represented as far as sex, ethnicity and sexual orientation. Gender identity is a little bit tougher though...that's where the personal presentation issue can come into play. I would have no issues with hiring someone who had completed her transition, but someone mid-way on the journey could be a little more of a problem. For a sales position, I think I can clearly say no. But for service or operations jobs, I wouldn't have an issue.
Great question...it really made me think.