I have TireMinder and the company is good to work with; however, a couple of things:
1. You don't need metal valve stems, some people think you do because of the rotation of the tires will make the stems wobble and cause problems. I haven't had any issues in that regard.
2. TPMS sends signals at intervals, not constant. So if you have an issue like a leak then it will detect it at the next signal sent. With a blowout, the TPMS will not alert you (don't ask how I know) and it is frustrating to depend on the system and not get a signal of a blowout until 30 to 60 seconds after you come to a stop!
3. TireMinder sent me a free booster after I called about two valves not getting a signal. Good company in that regard.
4. When I complained about the blowout and not getting an alert, TireMinder suggested I upgrade to a newer unit at $99, a "special price for a current customer".
Overall, having a TPMS is still a good idea but understand the limitations.