Earlier I pulled out my Yamaha student model 23 alto, just for fun as I hadn't played it in at least a year. I was blown away by how much I sounded like I did on my professional Selmer. The Selmer was slightly darker, but it was close. When I put my Series II neck on the Yamaha, it was almost too close to call. AND...some of the slight differences I noticed I would bet have to do with the fact that the Yamaha probably has leaks.
Point being, it really doesn't matter what horn you play on, necessarily. With enough practice, you will always sound like you. Equipment won't magically make you a good player.