Alum of both schools here and I do have to say that Texas State travels very well. Especially for FCS, Talk to UH or TCU or even Southern Utah about TXST's fans traveling. I really hope that UNT gets it together. I want to be interested in both schools again. I have to admit that I do follow TXST more closely but there is reason to believe that they will be outdrawing UNT regularly (they travel better already). They already have an instate rival in UTSA (who was in their first year yes, but drew amazing crowds this year). UNT would fare much better in the WAC.
In the WAC, UNT would have TXST and UTSA along with whatever out of conference games scheduled and Latech. I just don't see a downside for leaving the SBC behind.