I went with the Jacobs Exhaust Brake on my '06 due to the warranty issue... and wish I hadn't. With only 35k miles on the truck, the vacuum pump for the jake brake locked up, broke the serpentine belt, snapped the tensioner pulley, and sent it through the radiator shroud and into the radiator.
After doing some research, it seems like many of these vacuum pumps give out after 30k - 40k miles. In hindsight, I would much rather have a non-dodge warranteed brake that is going to last 100,000+ miles without major service, than to go with the Jacob's brake and have such low quality.
A secondary problem with the Jake brake, is that the vacuum pump requires a longer serpentine belt to be used; for this reason, I also carry a stock length belt to bypass the vacuum pump when it goes out. However, even this does no good when the tensioner snaps as well.
I like the Jacob's brake, but if I had it to do over, I'd definately look at the Pac Brake. --Eric