I'm also a TST fan. When I first purchased, I had a couple of issues. One was the extension on the inner dual. I called TST and they recommended a brand that solved the problem. The second was a reception issue. They had me try a couple of things until it was determined that I needed a repeater. Once the system was up and running, it has been problem free.
I've replaced the batteries once, along with the O-rings. They're very simple to service.
Recently, I changed to the color monitor and had some programming issues. I called TST and they quickly resolved the problem.
I have to say, TST has some of the best customer service you could ask for. I know one gentleman there works late and often answers the phone after business hours. That's real service to me and someone who is proud of their company and product.