The ride is a little firmer I believe as I recently drove a friends 2017 3500 4x4. In 2009, the reasons to purchase a 4500 were huge: the Aisin transmission the biggest, the longer wheel base, and a C&C turns tighter than the HDs due to narrower frames on the C&Cs, 52 gallon fuel tank, DANA 135 (heavy duty components) and the other big advantage to me is having the tow body. I carry two 12 ton jack stands, wheel chocks, a gallon Amsoil, AT4, power steering fluid, and tow straps. I have full tools, and carry an extra 60 gallons fuel. My friends who travel with us are always planning fuel and DEF.
In 2017, 3500 HDs have Aisins, 385 hp 900 ft lbs tq and get better fuel mileage. The C&Cs advantage now would be tow body, but you would need to buy a Smarty.
I put the emissions back on due to traveling in states that enforce them. EGTs not a problem except when it's regenning. Ron