That would be sweet if they could coexist. I actually tried once. I had a divider so only the gt could go in and out but every time he went out the umbee didn't want any of it. Only tried it for a week though.
It's funny how some people missed the just kidding lol. I was all ready to explain to you how the umbee gets more than twice the size of the gt and it would never work lol. How much you want for that umbee?