I’ve got Alpine rims (CX-ray spokes) and have often used them for general XC rides in the Dales (they’ve mostly been used on the canal commuting bike). I used them regularly for Dales XC in 2011, but not last summer very much as I was worried about the lightweight hubs in the crap weather last summer. I’m 13 stone, when they’re on the bike I avoid jumps and drops or barrelling down big rocky tracks, but that’s looking after them rather than knowing their limitations. I don’t know the weight difference between the rims, but if it’s negligible then probably go Crests.