From what I've read, NO "factory" probe on any smoker is worth anything. They are all junk. I run an Igrill with 3 probes ( 2 food and one grill. ) I've given them the boiling water / Ice bath test and found them to be close enough. I also use an Auber PID for smoker control, and that is with in 5 degrees of the IGrill, ( More like the IGrill is within 5 degrees of the Auber!) I did get wacky reading once on the IGrill, but I just unplugged the probes and re-plugged and it was fine.
If you brine, make sure to wash under running water, smaller pieces of bird only need a few hours, save over night for full birds and butts, and then I don't have salt in my rubs.
Usually I dry brine ( just rub a KOSHER - yes it is important to use kosher - on the outside of the meat, then and park in a zip-top bag in the fridge or cooler with ice)
Good thermos make all the difference. Yeah, they are costly, but cheaper than food poisoning!