So I have experiences I can share about 3 different dealers in Texas:
HOUSTON, TX;
Initially I bought a 2012 Zero S and my girlfriend bought a model XU from the dealer in Houston (Gulf Coast BMW / British USA), and had no real problems with the sale, the folks I spoke with seemed fairly knowledgeable and helped us get the Cash for Carbon trade-in credit, and all was well. Unfortunately, shortly after the purchase my girlfriend was in an accident and took her bike back to the dealer in Houston to get it fixed up (plastics, handlebar, basic repairs). She wasn't going to ride again for a while due to her injuries, but the bike sat there, and month after month we'd call for a status, but nothing would happen (and this is after we bought two motorcycles from them, and her father had bought a couple of non-Zero bikes from them over the years). I also several times asked to buy racks or other accessories for my Zero, and was promised phonecalls that never came. Unimaginably bad service. They claimed they couldn't contact people at the Zero factory, meanwhile I myself was able to several times.
Meanwhile I start having problems with my Zero, and the factory started dealing with me directly because the dealer was totally unresponsive at this point. I replaced my own motor, sensors, etc and the folks at Zero were incredibly helpful where the local dealer had been a disaster. Eventually my understanding is that the local guys stopped being a dealer for Zero altogether, though I see that they're now listed as a dealer again. I can't imagine that they've actually gotten any better, and in talking to other guys in town that ride the Triumphs and BMWs that seem to be the staple of that dealer's business, they seem to be almost universally despised for simultaneously overcharging for terrible customer service.
AUSTIN, TX:
I got (warranty) repair work done at AF1 Racing in Austin, TX and they were fantastic and knowledgeable! I'd highly recommend them. When I bought parts from them or did a test ride of a later model Zero they were great to work with.
Their repair guys I especially have to commend because of how much time they spent troubleshooting problems with me by phone and email, even after they'd already been paid.
DALLAS [ALLEN], TX
When I traded in my 2012 Zero for my 2014, I shopped around to (almost) all the dealers in Texas. Ultimately I ended up going through Maxim Motorsports in Allen, TX (north of Dallas), and they were knowledgeable, responsive by phone, and great to work with.
Anyhow, I don't know if this is any help at all to anyone in the Gulf Coast but that's my $0.02 (minus inflation).