Nothing wrong with either set-up, but for similar money I would get the
CDS. The
CDS unit should be good for an easy 10,000 hours and over 100,000 miles on the odometer. There are two things to consider though:
The smaller Chevy transmission is prone to early failure, but this can be avoided by either installing a shift kit or keeping it out of OD drive when driving in town. The heavy duty transmission has no issues. Do a transmission fluid and filter change every 25,000 miles, and add an external cooler if it doesn't have one. They're inexpensive insurance.
If you have long distances to cover between jobs and estimates, or like to drive your work vehicle to the store, and the beach, and tow your boat... you will wear the van out long before the unit dies. In that case you'd be better off with the slide-in you can more easily move from truck to truck.