I agree that the Super Flys are a much more capable fork, but they're really too long for the 93 geometry, so I'd say it depends on the kind of course it is, how well the XCRs work and whether you're going to need the sharper handling that the XCRs should give you. Hopefully as it's eight hours it won't be too tight and technical though!
One argument for the XCRs is that you'd get hugely more respect - whatever your result, people would look at the forks and think 'wow, that guy can ride'. With the Super Flys, they'd look at you not the forks and maybe think something a bit less charitable!