I think they max out around the high 500's (572 seems to stick out). They are nice units. I hope the next one is expandable. Like being able to monitor multiple meat temps.
I would even like to see it iPhone compatible, where you would have to transmitter at the pit and then you could customize multiple temps on the iPhone (meat and grate temps) and label them, like Pork Butt Upper, Turkey lower, Fatty middle....or something to that effect.
Performer 22 / Copper OTS 22 / WSM 18 / Black OTS 18