There's just no way it costs them more than a few hundred more than the a3.
I mean everything has a markup but 4k to change from one tower to another when it has no real features other than it folds lower is bananas.
I guess the people that need it really need it and will pay for it

Whether the rear ballast is "subfloor" or not is really just semantics. My SA is subfloor but it's still bags. Only difference with the Mojo is it doesn't have the little piece of fiberglass covering the bag.