while some of the aspects of those wheels impressed me, i'll never really be in to them. i know people who love them - they say they're fairly light, very strong, have smooth and resilient bearings.
however, the handful of people i know who use them have experienced a handful of problems that require some above-average wrenching and parts aquisition, meaning that having a bike shop that knows these wheels and can quickly get small parts from mavic has been crucial. broken axle, broken spokes, effed bearings... a proprietary lockring that leaves something to be desired, an odd chainline (which is actually the least of my concerns - it's easy to respace a chainline by getting a different bb spindle).... just enough to make me wary.
not to say that everybody experiences these problems - that's a ridiculous generalization - but i've seen enough problems that i wouldn't want to deal with them.