Tom,
Maybe you would know?
Beal made part of his case by saying cryogenics were harder to handle, and (I think) partly because of the pressure tanks required. But if you need to support upper stages doesn't that required strength go hand in hand with the pressurization? Also just the unpressurized weight of the peroxide must be hard on the infrastructure.

Also he was using carbon composite engines, but if Boeing can do an H2 engine with an ablative bell, isn't it likely we'll see other RP-1 fueled engines that forego regenerative cooling (could still be reusable eventually by replacing the bell)?