I'm using a dual probe Maverick. I love it. Since I now cook on a treager, I don't have to worry about the smoke chamber temp so I'm buying another meat probe so I can monitor two Butt's, birds etc. at the same time.
If you decide to go with a refurbished, make sure there is a return policy. Upon receipt of the unit, run a quick calibration test (just like you would do with a new unit) and if it calibrates correctly, you should be set. If not, return the sucker and ask for your money back.