I drag when going over humps,
Hi Lynn!
Wondering what you mean... I have an older 2350, but very similar in dimensions and weight to yours.* Also an E350. The only time I have dragged was on a steep entrance grade change going into a shopping plaza, and I did not hit it on 'the diagonal' like I should have, but motored straight in... definitely operator error.

Does yours scrape on things like speed bumps? I was VERY nervous about the generator exhaust pipe hitting speed humps, it is the lowest point on the rig and near center. Never has. (Whew!!) I tend to be a bit adventurous where I drive also, to judge from other people's reactions. I have been quite happy with how the 2350 negotiates rough terrain.
I told the service tech my Phoenix sags, he said they all do.
Even with the trailer on and loaded (fresh water with ~10 gal, waste tanks empty) I dont have any noticeable 'squat' on the back. I have not made the time to get on scales yet, however. Compared to many full-timers, our 'getaway' packing of the coach may be MUCH lighter. Can you possibly post a picture to illustrate the squat yours has?
And now down the rabbit hole...

I agree with Hutch42's assessment that the supplied components now are not of the same quality. I am finding this constantly in the utility cart world also. Club Car has gone from King to 'just another player' with their series of downgrades to quality and life-span. Our carts from 1996-2014 are in service more than the 2015 and up ones we got. We are looking at other brands for the first time in 30+ years, and finding they all have gone to a common low level.
I am a Craigslist junkie, and constantly monitor the RV for sale in our area and south of here to Miami. Its where we found ours. Prices for older (~10-15 years) B's and B+'s have increased much over the past year. I think we could get easily $5K more than we paid in Oct 2017 for ours now, judging by the prices I see now. ( we paid ~$21K before taxes, etc.)
Right now on our local Craigslist - 2007 Dynamax Isata 282 - $62900 (30K miles, 28'), 2004 CHINOOK SUMMIT - $45000 (135K miles (!) 27') , 2008 Coachmen Concord 275DS - $52450 (35K miles, 28')
On this forum the only one old enough to even be a comparison is a 2009 2551, ~30K miles, $52,900. (Hey...its over in Brooksville! We go there.

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Now granted, these are all 2-4 feet longer, but I dont see that as an asset. For a E350/450 chassis, I dont like anything over 25 foot. I feel that overloads the chassis. I would either move to a small A at that point, or get one of the larger C's based on the class 6 chassis. (19-24K GVWR instead of the (barely..) class 4 E450 14-16K GVWR)
I feel we got a GREAT value with our purchase, a 2006 with 40K miles. We have been under the assumption that we would be working our way to getting a new one built to our specs around 2023 or so. Looking at the quality issues that the supplied parts are giving, and the radical rise in prices...might pay to put $10-15 K into ours in improvements, and have a much nicer and 'better quality' result for ~$45K total. I dont need 'new'. Dependable and proven are my benchmarks.
* forgive my ignorance, but I base this on looking at the PC website specs. Looks like a 2350 and 2400 are similar (within a foot) sizes, and in content, but different interior layouts. Are there any major differences in accessories or undercarriage layout that would make them handle much differently?