It's state law in TX that the Tesla guys can't discuss price. Sad really.
It's difficult to cross-shop these cars from the standpoint that other than tq/hp, the cars diverge on pretty much everything else. You certainly won't lose the thrill with the M4. Tesla owners who are in it for the driving aspect are
beginning to grow bored.
I purchased mine from out of state and had a great experience doing so. I however knew what I wanted and didn't need the comfort of a dealership building to make the decision.
Houston dealers are also less willing to negotiate on purchase price, so it depends on how flexible you are in the buying process. As far as service geos, let's just say that I'll be taking my car to BMW of Austin to get work done since I've experienced both.