New instrument woes. B or Tenor trombone?

This could be a bit boring to most, so I will reward all who read and answer with a cookie. But anyway, let me first state that I am willing and pretty eager actually to expand to the b trombone. Time is all I've got. My decision couldn't come at a better time because we just lost our two and only baritones and we won't be getting anymore until 2 years from now. So here's my problem, I'm 3rd chair in my section and I'm in need of a new instrument. I'm getting off of my straight horn finally. But what made me see the light was a school b trombone that hadn't been rented out in years. It was a single rotor and I figure I learned pretty quick on it and I would like to switch to a double bbone and grow into it. I have found one and acquired funding for it. So what's the problem?:My director(s). I brought it up to them and they told me I made a good choice in the make of the bone. Even going as far to mention in quote "Jupiter B Bones are amazing". But almost in that same second, the other director told me I would be better off with a tenor with a single rotor. He went on to talk about trombone "Hierarchies" in college. I understood what he was getting at. But it was no definitive yes, go ahead, or DO NOT UNDER ANY CIRSTANCE GET ONE YOU FOOL. So here's where the yahoo answers community comes into my plight. I was hoping to get some kind of advice, knowledge on the cirstance, and maybe the pros and cons of either decision. If I'm over yzing, please don't hesitate to tell me. Thank you and have a pleasureful day.