^^^ I've said it before and here it's being said again! Huge Improvements! You'll notice it Parked, too.
Since this member's a racer... There's talk, and truth in it, about how too much front/rear "roll stiffness" can contribute to under/over-steer. I have no doubt it's true in the racing world. Just not applicable in the RV world. Stiffening the front and rear on an RV, particularly an E-Series with Twin-I-Beam "Swing" axles, just doesn't have a downside. Might "on paper" but not In Use. The RV operating envelope is nothing like racers, even ordinary daily drivers. When the E-Series sways, it steers. E-350 and 450 should be the same in the front axle/suspension. That, or I missed some interference that's actually there...
Yo! SteelJag! Oftentimes, we hear from an owner whose E-Series based Class C drives just fine. I think some of that sentiment may be based on conditions and expectations, but I also think part of it is luck-of-the-draw.
I can offer several possibilities why a given coach would handle better than another:
New parts or no worn parts of course
Wheelbase and Floor Plan allow for good weight distribution
Proper loading for good weight distribution
Tire Pressures set according to Actual Scale Weights for Front and Rear Axles
Front End Alignment intentionally or otherwise set to reflect motor home load and usage. Especially CASTER, should be 5* or more. Range is 3-7* and the mid-range of 3* makes steering very vague.