It failed because because it didn't have enough power or torque to upshift because the ratios aren't well matched to the 6.4. I doubt it would be an issue with your trailer or most situations, but it does hamper the engine. There was a guy from Colorado on here a month or two ago who was ready to trade because he ran into similar issues as you saw on that YouTube video. I'm not sure what came of it but I'm sure you can search and find the thread. He got stuck going 30 mph or something on some grades. Again not likely something you'll run into very often. I think not having the exhaust brake maybe a bigger tradeoff. That thing rocks.
