We have a 24 foot Class C on the E450 chassis. Like Desert Captain, we have had zero problems ... solid as a rock and I can drive down the highway with one hand on the wheel. However I feel that our rig's handling and stability is due to the fact that the chassis is so underloaded by the coach, the coach has a fairly small rear overhang, and the coach has a small enough wall area to keep wind pressure low.
We had an alignment done after owning it for a few years, but for no reason other than you're "supposed to" ... and they did install the shims. We had no problems before or after the alignment. We have almost 50K miles on it with the OEM shocks. Tire pressure is 80 lbs. rear, and 65 lbs. front ... and the tires are non-stock size Michelin LT M&S2. For our chassis year Ford installed both front and rear sway bars on the E450, but only a front sway bar on the E350. Now, I believe that both the E350 and E450 have front and rear sway bars.