In the Houston area, the Memorial Park repeater and the Channelview repeater both still get some traffic. Not as much as when linked but still you can have a nice chat every once in a while.
I second what @WRHS218 said. Once you join Texas GMRS Network you will have access to a lot of repeaters, many of which are not listed here. MyGMRS.com has a much better forum though.
I've been using a UT-72 with an AT778-UV for more than an year now and have not had any problems. I almost always get good reports. When I don't get a good report, there is usually an obvious reason like weather, distance, trees, buildings, etc. This is a very inexpensive setup and I'm quite pleased with it.