If you like the smoothness and quietness of your 1500, then it might be best to stay with a 1500 for that amount of weight if you are also going to use it as a daily driver.
The 2500 will tow the weight with much greater stability and less sag, but it will not be smooth and quiet like a 1500. You will also loose about 2-3 mpg in the 2500 Hemi versus a 1500 Hemi due to the added weight of the truck. Stick the the 1500 and just get the air bag option or beefier aftermarket coils for the rear like Tuftruck coils.