I use the maverick et 7. It has two meat probes. I just stick one probe through a small piece of wood to measure grate temps. I installed a thermo in the lid of my Brinkman. Most of the time I use my probes for 2 pieces of meat, because I know my grate temps based on the lid thermo, which I calibrated against the maverick. The ET 7 can only be set to alert you when you go higher than a certain temp. The et 73 can alert you if your cooker goes low, and I assume high also.
The Maverick is the only wireless digital thermo I've ever used. And unlike almost everyone else, I'm not impressed. It's cheaply built, and the wireless range is not good. According to most reviews I've read, there isn't anything better out there though. Not trying to poop on your parade. But you may want to read reviews of several brands before you buy one.