Agreed, not that hard to find. Not as prolific as the Denali or suburbans, but resale is similar to a denali, I found.
I needed the 3/4 ton for the additional towing for my new ~7500lb travel trailer. Selling my 2003 Denali XL was pretty difficult. I am used to the new truck now, but it is definitely a truck with the 3/4ton suspension, but has good power with the 6.0 liter and 4:10 gears(optional with the 2500).
The differences are 6.0 liter but optionally you can get the 4 or 6 speed tranny, the axle 3:73 or 4:10 towing gears, tow mirrors, leather, and other interior options, but about the only visible difference between the 1500 and 2500 is the 8 lug axles and the rough ride due to stiff suspension.