Here are my thoughts on pflasch's opening question.
If I was the final decision maker at Phoenix, I would not be offering a Transit (with it's current weight limitations) because the company has a proven track record with it's design and processes. It doesn't make sense to come up with something totally different that is light enough for the Transit. Phoenix would need to introduce a totally new construction process AS AN OPTION for just a few of their smallest models. It does not make financial sense unless the E350 and E450 became unavailable, forcing them to re-evaluate everything.
Now if Ford came up with a heavier duty Transit that is comparable to the Sprinter and E350, that would open opportunity for Phoenix to offer that chassis. I personally feel a 2350 built on an imaginary Super Duty Transit would be "One Awesome Rig".
If Ford later does not improve upon the Transit enough to carry enough load, and they dropped the E350, but kept the E450, it wouldn't be the worst thing for Phoenix to remove a rear leaf spring or two on each side of an E450 to soften the ride for their smaller models. Then they could keep everything the same to keep doing what they are so good at.
A few weeks ago, I had the opportunity to compare the Transit cut-away to the Sprinter cut-away chassis at the Chicago auto show. There is quite a difference between each and between them and the E350. One thing certain, I understand much better now why neither of them can have their wheel bases modified like the E350 and E450. It seems near impossible to precisely cut a hollow thin-metal two-piece-tack-welded box frame, add or remove material to adjust the wheel base, then rejoin the frame. There would be too much inconsistency in the process, and the material is just too flimsy, like working with flexing sheet metal instead of a thick solid steel frame.
For the curious.....
Getting into the Transit is like getting into a mini-van. It sits much lower. Getting into a Sprinter is like climbing into an E-Series. It sits much higher.
I don't have pictures of the E350 and E450, but they have a nice thick "C" shape frame that is easy to manage for frame adjustments. The E350 is naturally a little thinner than the E450.
Here is the Sprinter. Note the two piece box frame with a mid-point flange on the inside and outside where they get tack welded and glued together.
Here is the Transit. It's box frame is a "U" with a flat stock top tack-welded and glued much in the same manner as the Sprinter.
