I am in the market for a high end 45ft coach, the models I have been interested in come with very powerful diesel engines, approx 600 hp and 1900 ft-# of torque. I will be towing a stacker trailer with a payload of approx 6 tons (two vehicles plus gear). These coaches have an option of a 12 speed ZF transmission or the standard 6 speed tranny. My question is to the experts out there - is it worth purchasing the 12 speed tranny when there is that much torque and hp in the coach and would I notice the better performance? Also would the 12 speed reduce ride comfort with all that shifting?