I run the TST system & love it. I use the thread on sensors w/ the user change-able batteries (batteries last about 18 months) - I buy the batteries 10 at a time and get them for about 35 cents each (off the internet/amazon).
IMO monitoring pressure alone is not enough - TST monitors Temperature too.
Air Compressor - Since the coach has a compressor, i carry a hose & fittings. I also carry a 10 lb Co2 bottle (higher pressure & completely portable (no power needed), great for off-roading in the jeep too...the fact of the matter is i rarely use or need the c02 tank or the coach compressor/air-line.
Once you have a TPMS system you'll rarely have to mess with the tire pressure, no need to check the pressure before or during a trip - just turn the monitor on.