The qc has a standard 1500 frame with standard springs and no 5th shock or above the rear end to stop the wheel hop. It doesn't handle worth a crap through corners (I tried one at the SRT track experience and they did not even put one out on the road course) - It did ok down the drag strip in tow haul mode, but there is no comparison to the 6 speeed.
I haven't heard of any problems with the transmission except for differences of opinion on the shifter itself some like it stock most dont. Good shifters are available from our vendors here on the site that most like.
The premise of the whole truck was to make a performance truck thus the Rc which is built on a 2500 diesel frame with other enhancements not offered on the qc.
There are a couple of very fast quad cabs on our forum, but I say RC hands down :rock: