I've been skating a set for a month or so now.
I think I saw someone mention that they're like Spitfires version of STFs. Whoever said that was wrong as hell. These feel nothing like STFs. STF's are real slick and slidey, as opposed to the F4's which lean more on the grippier side when compared to STFs. Don't get me wrong, they have some slide to them, but if you're buying a set thinking you're gonna get the same slideiness as a STF wheel, then you'll be disappointed. I'd say they feel somewhat close to a SF classic in terms of how they slide and grip, just a lot more durable than an SF classic. No flatspots or little chips out of the wheel yet, so I'd say they're holding up very well so far. I don't have a car so I skate everywhere, and there's some pretty rough asphalt here, so I usually wear down wheels pretty fast, and I've noticed that these have shrunken down a teeny bit, but barely at all, so I'd say they're wearing out a very good rate. Overall I'd say they're pretty damn good wheels.