I've owned now two of the K2 platform. First was a 15 Burb with a 6 speed, and now a 17 Esky with the 8 speed. Coming from the 4 speed to either of these is a game changer. The 10 speed has better gear programming in the TCM for gear selection, but I hatE the constant gear changes. I bought an 8 speed due to there being minimal failures of hard parts in the transmission vs the 6. The torque converter in the 6 speed is the weak link, it takes out the pump normally also.
I think if you get a 6 speed or 8 you must do the trans cooler bypass reprogram. This keeps the temps very nice in the trans so its not running stupid hot all the time. This is a must if you plan to keep one of these rigs. This done with a trans service helps prolong the life 10 fold.
Turning off AFM is best you can do, but keep it on a 4k oil change cycle, no matter the monitor. The main failure of AFM seems to be dirty oil building up and causing things to fail. So these two things together should help make it last.
As said prior, ac condenser failures are possible.
Check out the carfax, look for maintenance, and large repairs that were reported.
After a die hard NBS and NNBS, making the change to the K2 was hard but worth it. The handling improvement is night and day. Now the NBS is a very utilitarian vehicle, no major frills, less to break also, and has lasted the test of time. Live it up, make it happen, its a good time to buy as most dealers are ready to deal....