I use a TireMinder A1A with 10 sensors. I came with the repeater, which is mounted under the bed in my MH. It works well and they have free battery replacement if you register your warrantee card. The batteries last 1 season (9 - 10 months). I change mine every year when the MH comes out of storage after New Years to head south. Have never had a sensor quit because of a dead battery.
As for detecting leaks? I can't really say as I have yet to have one. Knock wood. I preferred the A1A to the Smart TPMS because I did not want to have my TPMS reliant upon my phone. I have ruined my phone a couple times with mishaps. The A1A comes with a suction cup mount and USB charge cord for it's internal battery.
I have heard good things about the TST 507 from friends, so I think they are probably about the same quality.