The probes are I believe either 3 or 4 ft. They are long enough so that you can hang the unit off the handles of a Kettle or the mini. If you want to get a 6ft probe you can place the unit on a table near by.
You are thinking too deeply into the whole 2 probe thermometer. The stock unit works great (as approved by numerous brethern) If you are within warranty period Maverick will replace items that are defective. If you are hesitant to get the Maverick, it might put your mind at ease a little bit more than Big Green Egg is willing to put their name on the device and sell it as an eggsesory (
http://www.biggreenegg.com/eggcessories/dual-probe-remote-wireless-thermometer/)
Remember though you get what you pay for. The thermoworks dual probe setup is a very nice setup. My co-worker has one and loves it. The overall quality of the unit is higher than the Maverick ET-732. But if you want a remote receiver you can carry around the house, you will have to find another solution for you as they do not provide one.