I haven't been to Fenway as a patient, rather I've been at the facility for community and volunteer work. It's an amazing place, I haven't used them as my insurance would require that I have a PCP there **and AFAIK, my insurance also doesn't allow me to have a PCP that's not within the university's medical practice**. It might be that I could break that catch 22 by asking for a transexual specific PCP but my PCP has been fine at least in that regard.
Sorry to digress, I'm sure you'll need a referral but they should be in network for most insurance and I can't imagine you won't be happy with their care, certainly you won't be talking to people you have to educate on trans issues :-).