Ze Germans are known for their conservatism. IMHO Ford and the rest of the big3 are really engaged in a marketing D*** measuring contest with those outrageous tow and horsepower figures. I wouldnt tow 12k behind my F150 regardless what the marketing types say.
A look at the comparison page on the Sprinter website shows the 3500 Sprinter with the 2.1l or 3.0l Diesel with a reasonable tow capacity of 7500lbs and the e350 with the 5.4l or 6.8l having 7400lbs. The 2015 Sprinter Van. Built to Work Smarter.
Looks like the Sprinter beats the e350 in towing slightly, and it does it with 1/2 as much engine.
Maybe we get more # in Canada ? 10,000 of 'em, per Ford.ca:
2014 Ford E-Series Wagon | View Full Specification Library | Ford.ca
Unibody vs. Full-frame - I'd expect a Sprinter to be lower for towing. Ever see a unibody Highway Tractor ?
Scooby is perfectly able to speak for himself..... that said, I'll put my 2 cents in, as I think we are drifting just a bit....... many of us in this thread look to these compact trucks as a daily runner, that can also comfortably tow 5 to 7k lbs.
Personally, if I'm heading towards 10k#+, I want a full-size platform, framed, with a long wheel-base.
Rgds, D.