Most E450 driving problems can be corrected with Tire Pressure, Alignment, and a few chassis upgrade parts that really aren't all that expensive.
But there IS an exception - IF the Wheelbase is not long enough, the weight distribution will be Tail-Heavy. Sometimes weight can be shifted but every once in awhile the imbalance is simply too great. If you can get the specs, a "31" (just in my opinion) needs WB well over 200-inches. Our 31 for example has 218" and the rear axle is below its max rating. The front axle is very close to rating. This weight on the front tires gives it something to steer with. I've heard two versions of weight balance. One is that the FRONT needs to be at least 1/3 of total scale weight. The other is that the FRONT needs to be at least 3/4 loaded at scale weight.
So, Specs and Scale Weights. If you can get those, you'll have a good idea what handling can be. Many here have done upgrades. Many have also been satisfied right out-of-the-box.
Holiday built bulletproof Class C's in the 1980s, we had one. They stopped building them awhile and then brought them back. Probably under the Holiday name but actually built by one of the many companies Monaco acquired (Holiday being only one). Some of those were well above average, with features like an aluminum roof, but I don't know about all of them.