Many of us are very happy with TST 507 systems.
The flow thru sensors allow you to add (or remove) air without removing the sensor. But some have mentioned that the air flow when adding air thru those sensors is very slow. And they are heavier than the standard sensors.
I have the standard sensors (not flow thru). Not a problem for me. I remove mine in Oct/Nov. In late March or early April I check the tire air pressures. Invariably I add no more than 2-3 pounds of air to each tire and put the sensors back on. And I do not have to add any more air thru the travel season. And have never had a tire go low during a travel season. Only takes a few seconds to take one off, or put it back on if needed.
TST 507 has user replaceable batteries.