I have a MDT and tow a 15000lb 5th wheel with it. My prior TV was a 1 ton dually. The MDT makes towing a breeze. Especially down hill. Mine is equipped with an exhaust brake which holds the truck and trailer at 55 MPH on a 6% grade, I never have to touch the brakes.
To be honest, I would have gone with a HDT instead of the MDT because the ride is better and it's a lot safer to tow with. Plus the HDT would have been less expensive to buy and probably last longer. The only problem is my 94 year old dad goes with us and there was no way I could get him up in the cab easily.
The MDT rides rougher than my old dually when empty. Some of that can be fixed if I spend $2500 on custom springs for the front. It has air ride seats, cab and rear suspension which help smooth out the big bumps.