(BTW, kids, if you ever want to see what a successful act of espionage looks like, look at this: it would look like Boeing shooting off its own foot and then the Pentagon shooting off its own foot in response, both in ways that "accidentally" benefit Russia and make us dependent on them for space access.)
I don't know what this says regarding the possibility of further success for SpaceX; they've moved to a less dense fuel in hopes that it'll allow them to have self pressurizing tankage. While SpaceX has had increadible success I find myself wishing there was a way of wedding Elon's money and drive with the people who built DC-X in hopes that they could maybe, MAYBE, get more than one or two flights out of each test vehicle.
IF you could get cheap RL-10's for the price that the DC-X project was buying them for in the 90's, I'd suggest using them, suitably modified to burn methane, _just_ as a braking/landing engine. [2]
(But that was way back in the 90's, when the MIC was still sometimes running assembly lines instead of building each single engine by hand).
(Oh, and I found a slightly better ref. on RL-10's: [3])
[1] https://yarchive.net/space/rocket/fuels/hydrogen_deltav.html
[2] https://forum.nasaspaceflight.com/index.php?topic=11020.0
Frankly Delta Clipper was even more impressive given that it came from MDC who were by far the most conservative defense contractor. That sort of thing would have been more typical of Northrop.