I've been riding spitfires pretty much exclusively for the past 10 years. I've tried a few other things here and there, even jumped on the stf craze a few years ago, they just felt horrible, way to slippery and hard. not to mention the shapes are completely miserable, so much so that I would prefer a yellowing flat spotted f1. However, these past year or two I've ridden mostly spitfire classics, all of which for some strange reason haven't yellowed or got any substantial flat spots, and have out performed every f1 set i've had. I'm stoked to try the formula 4 wheels.