BigSix1, the leaf sprung F-250 TTB is NOTHING like a '72 F-100 2WD (twin I beam, coil springs) or an F-150 coil spring TTB. Both of those are good suspensions. in fact, they are the basis for a lot of desert racers.
The problem with the F-250 TTB is the combination of TTB with leaf springs. As the suspension cycles the beam makes the end of the axle swing in one arc (around the beam pivot, moving the axle end right to left as it moves up and down) and the spring makes it swing in another (around the fixed end of the spring, moving the axle end front to back as it moves up and down). The beam won't let the axle end move front to back and the spring greatly resists right to left, so the suspension binds up.
It is a terrible design, but overall it does work. Some people even like it. Rebuilding and keeping an F-250 TTB isn't the worst thing in the world to do. But most people do think the F-350 solid axle setup, which doesn't bind up, rides better even though it's a 1 ton compared to the TTB 3/4 ton.
There are still reasons to swap a solid axle under a coil sprung TTB F-150, but ride quality is not one of them. But the F-250 TTB is a whole 'nother animal.