I fitted a pair recently, but hav'nt done enough mileage to guage much.
They seem to run well, but some members have said they flex a lot. Can't say ive noticed . I guess if youre racing or really really pushing them, they may show some flex, but for normal riding / commuting, i'd say they were good value. (i got mine from Fatbirds @ £68 ish...i have seen them in Cycling weekly, Parkers perhaps, at a smidgeon over £70, and that included tyres and tubes as well )
One thing, i did have a hell of a job to get Conti Ultra Sports on them