Before I owned a diesel with an exhaust brake I owned several D/A's and the grade braking worked pretty good, (in T/H)....on some of the steeper grades I'd run, I'd have to use my brakes and/or use the trailer brakes manually to slow down...now the GM/Chevy D/A also has an EB.
When I purchased my first Dodge it had an EB, it was awesome when in T/H, never had an issue....the 13' in my sig. has improved from the 2010, Towing my 5er in T/H mode with EB on first stage (most aggressive), I've gotten to where when I go down a steep mountain and put the truck in cruise control,at say, 50-55 mph and the truck will maintain that speed....couple examples, I26 DOWN Saluda Grade in NC, I64 going DOWN from Beckly to Sandstone Falls WV, (7% grade), and I26 coming out of NC into TN. I do not have to give throttle and do not have to brake ...its awesome:).
I've went down I26 from NC into TN with EB and T/H on sig. truck towing sig 5er loaded to 16,000#, and not in cruise contol, just taking my foot off of the throttle., truck will almost bring me to a stop....I feel a whole lot more secure now than I did before...
If one has EB and T/H on a diesel which the Big 3 does, I don't see a problem when towing with all those "tools" ON......really not an issue any more with the newer diesels, and Ive had gassers towing 5er's (last being an 8.1, D/A's , and now diesel with two stage EB, TH and it works great):)
One thing different about the Ram, even if NOT in T/H, the EB still works and can be rather agressive....