You do not want to put an Edge J/A on a Duramax. Nothing but problems.
I'll second duramaxforum.com I've been a member there for years.
Saltbranch, if you are kicking the tires on a new Duramax you won't be able to program it with much yet. There are one or two box units, but the custom tuning is being worked on by Kory and I'd think it'd be available within a year or so. Some issues you will have... automatic voiding of factory warranty, DPF, DEF. The ECM's in the new truck will record any modification permanently, and will alert the tech at the dealership when he plugs in.
I find that it has a lot more power stock than the older Dmax's. Nearly 800 ft lb of torque, and 400hp from the factory. I almost (emphasis on almost) don't miss my tuned Dmax. The DEF is a slight PITA, but the EPA requires it on all diesels now. I've got 11,000 miles on my 2013 now, and she's running like a top. 20-23mpg (hand calculated) on the highway, 17mpg towing my 3500lb boat. Also 18 mpg combined city/hwy.