I have several 3.7s in my fleet. Transit (HD 350s), PI, and a 150.
Personally, it is one of my favorite engines for fleet use. (Fleet means I want it right-sized) Very reliable, not high-strung. I will take 3.7 all day and any day.
I will second the 3.7 vs 5.4 comparison. I have some older E350s with the 5.4 and while not under load, the 3.7 is leagues better (and gets about 40% better fuel economy with my use), it is ALMOST there with a load (about 2,000-3,000 of payload) but that is the 350lbs vs 285lbs of torque difference. We load & unload all day long. So with your 2,000, the 3.7 will do that with ease although you will notice the higher revs. It makes peak torque around 4,00rpms compared to 350 at 2500 rpms on the 5.4. Still, for me, that is plenty fine.
My 3.7 Transits do about 15 hours of continual operation a day 5 days a week. The 2016s have about 3000 to 4000 hours each on the engines and I have only had one throttle body issues to date. Our issues with the Transits are brake-component related but that was an issue on the 350s too. Ford just can't build a robust set of brakes for heavy users.