I think you have it wrong.

If you investigate TPMS systems used on heavy transport trucks (semi-trailers), most of them use a system that is connected to the inflation valve and measures pressure at the valve, by keeping the Schrader valve depressed. There is nothing wrong with that design - but the safety and reliability of it is, of course, very much dependent on good quality components and meticulous quality control during the manufacturing process.

I use the Garmin TPMS on my motorcycle, primarily because my GPS supports display and monitoring of tire pressure via Garmin supplied pressure sensor caps that fit over top of the Schrader valves. I have complete confidence in this system - I have used it for 5 years and 60,000 miles without any problem, and it did save my bacon once when I encountered a puncture from a large nail on the highway.

Like anything else, you need to be a critical consumer when purchasing equipment, particularly safety equipment. I don't purchase anything from unknown Chinese (mainland Chinese) manufacturers. Garmin makes their TPMS sensors in Taiwan, which is a totally different environment and culture from mainland China, and I have trust in Garmin as a manufacturer.

In reply to the original poster, who asked about TPMS in general, my recommendation is to purchase a system from a manufacturer that has a reputation for quality and dependability. Personally, I like the concept of TPMS integrated with the GPS because it minimizes the number of different systems on the motorcycle, and enables the manufacturer to easily update the software that operates the TPMS. The only downside that I have encountered so far is that the little batteries that go inside the sensor have a maximum life of one year, and it can be difficult to buy them when you are on the road because they are an uncommon size. This means you need to carry a couple of fresh spares with you.

Michael