I'm skating the 99a Hardline's after a friend of mine who gets wheels from them spoke highly of them. I've been skating them about 3 months now, definitely a bit less smooth than F4's, they have a bit more grip to them and feel less predictable when sliding but still feel very nice. If they hold up and don't drop in quality by the time I'm done I would definitely consider getting them again. In conclusion, are they better than F4's or STF's? No. But I like them and would say they're worth a shot if you feel like a change.