Those are the ones I know about. I have had minor radio and microphone work done by 4Gs, personally I wouldn't let them set my radio up. They seem overpriced and I don't recall them having proper test equipment. They have a decent selection of radios and antennas. I believe they sell amps as well. Its been over a two years since I've been in there so things may have changed.
It has been years since I had any work done by Primos, i know he was popular years ago when he was at the truck stop at the 785. Never had any experience with the other two, however I hear Tbone for miles and miles. Not sure what he is running but it sounds good.i can easily hear hi. in downtown Houston.
Really didn't give you much help here, but that's about all I know about the shops in Houston. I get my work done by Clay's in San Antonio and am satisfied with them.
What is it you are looking for, to buy equipment or have some work done?