I owned a 2011 Chevy Silverado 2500 with a Duramax diesel, and used it to tow my 2015 RPOD 179 which I bought a year ago. The Chevy worked great for the first 20K miles, and then things started going wrong. So wrong that it ruined a couple of vacation trips while towing the RPOD. Most of the issues were covered under warranty, but they were problems that I felt should not have existed.
About six months ago I decided to get rid of the Chevy and buy a new smaller truck, like a RAM EcoDiesel. When I saw the Chevy Colorado with a Duramax, I thought maybe I should look into it as well. During one of the many times my Silverado was in the shop, I asked the head mechanic why is my truck so trouble-prone. He said the 2011 was the first year for a major model change, and the first year production tends to have a lot of issues. Each successive year has less problems. So I asked if he thought that'd be true with the new Chevy Colorado and the Duramax engine. He said absolutely, since it's the first model year. I ended up buying a 2016 RAM 1500 EcoDiesel. I really like the truck, it's the 3rd production year, it's the right size, and gets close to 30 MPG.
This is just my opinion and how I saw things. I think you're wise to research your purchase. Good luck!