I love the ss 29er so I am thinking that the SS on the cross might be fun too. :hmmm:
I haven't done MTB SS, but CX seems to be harder to get the "right gear" as it's so course dependent. I did SS the whole first season on 36x16 and hated one part of every course because I was hitting the purple zone on some hill and then spinning out and getting dropped on the flats. In 2007, I did SS nats and similar, I would've killed for a 38, but my pre-ride was so slow on the frozen tundra there, that I underestimated race pace. Would've loved a 36 at HV.
Given my lack of racing this year (and new paint!), I'm going to do more SS. It removes the gearing factor, and to me is more fun, but also is a good leg strength/speed workout. With my geared bike I race, with my SS, I go hard. Hard to explain, but I don't get as competitive with my SS.
Plus the ride is awesome. Everytime I ride it, I wonder why I don't ride it more.