We installed the Bilstein heavy duty shocks on our Born Free with the E450 chassis and did not notice much of an improvement. This past Thursday before leaving for a two day trip I installed the Bilstein Comfort shocks on the front our 2351 with the E350 Chassis.
I am pleased to report that the ride is much smoother. We drove on some very rough roads through the center of PA into North West PA (Meadville) then across the top of the state on back roads to Bradford. It was a great test for the new shocks over a lot of bumpy roads.
We owned three Born Frees all with the Ford E450 chassis before we purchased our Phoenix. The Phoenix with these Bilstein comfort shocks and the rear Super Springs is by far the smoothest ride.
We replaced the shocks ourselves. The two in the rear were very easy, we replaced them several months ago. The front driver side was a challenge to change as the nut on the top is hard to get to.
After some researching how to replace the driver side I decided to bend a 3/4" open end wrench in the vise. The wrench broke when I was bending it and to my delight the 4" broken open end of the wrench was the perfect tool to reach the nut.............I do have a decent size scab on the top of my left hand to show for it.

I was determined to smooth out the ride on the Ford E series chassis and am very pleased with the results.
Based on our experience I would definitely get the Bilstein comfort shock over the heavy duty.
Dave