I'm still in serve for the holy grail and still playing with the good ole dependable Wilson Ultra FPK. I've demoed a few racquets with one of the better ones being the new Slazenger Pro X1 (even though that one may need a little customization). The SI rating of the FPK was a 5.0. Does that mean I should be considering the Hyper Carbon Prostaff 5.0 as a similar racquet? I've called TW and the person I spoke with said the RDC rating of the FPK was 66, not comparable to the HPS 5.0 at a RDC of 74. I hear there are some arm problem issues with that racquet. I think my dilema lies in the fact that the FPK has a tapered beam which I think gives it the initial power (thicker beam in the handle and throat) with the added feel in the head (thinner beam there). I think the Prostaff 6.0 95 is similar but not nearly as stable as the FPK. I start to steer towards a more flexible racquet. And then there's something in between - the HPS 6.1. I don't think I like anything under 12.0 oz. What do you think the most comparable racquet would be to the FPK? HPS 6.1?