See my threads about this for my full opinion.
We sold our 2013 Cummins a few months ago.
My next truck, whether it be a 2018 or 2019 will have the 6.4l Hemi with 4.10 gears.
The 6.4l BGE is a true HD gas engine...one very like my 8.0l V10.
The 6.4l will work like a Cummins, unless you tow in very steep or High altitude or over 65 MPH(most states have laws against that anyways),
Now the Cummins does offer alot more than the 6.4l Hemi(engine brake for one), but unless you tow regularly long distances at highway speed in hilly or high altitude, give that BGE a chance.
Gas motors do have a place in HD pickups, but the decision is yours.
I based my decision on not towing on the highway much(I prefer backroads at the expense of a few minutes faster drive), the maintenance and diesel fuel, and I just don't like the sound of a clattering motor...all my opinion.