I was just reading an old study from my "saved" folder on a test of Florida LMB around Ardmore, OK (a little north of the Texas border). It may even be the study that ewest was referring to.

Florida LMB in Southern Oklahoma

As a gross generalization, the study indicated that the biggest northern strain and biggest Florida strain were about equal at that location.

As regards "outbreeding depression", I would trust ewest's advice far ahead of my advice!

Overton Fisheries does carry a "branded" version of F1 LMB. (They are about 1/2 way between Dallas and Houston.) I believe Todd? Overton sometimes comments on Pond Boss and some of the people here that have worked with him say he is good at answering questions. You might try to email him during a slow period of their business and see if he can tell you how far north their F1 bass have been an improvement over northern strain.