Disregard this. H'es probably saying they suck for sliding or something, but believe me, after you break them in for a couple months, they actually slide pretty well. Probably not so great for ridiculous sideways slide gloves on the ground-kind of slides, but I have absolutely no problem getting my tail to kick out when I want to.
Reason I like them so much is just for the smoothness. Maybe they are supposed to have high rolling resistance or something? Either way, they absorb cracks/bumps like no other wheel i've ridden.