-- Last Updated: Oct-27-12 11:11 AM EST --
Any composite boat is going to paddle a bit better than a Royalex version, even if the Royalex boat is a very close copy in hull shape. The increased stiffness of the composite is a big reason, but the blunter water entry at the stems of Royalex boats makes a difference as well.
The main difference in the composite Wildfire and the Royalex Yellowstone Solo (nee Royalex Wildfire) apart from the material is that the YS has differential rocker, with an inch less at the stern. The Wildfire has sharper lines at the stems and shoulders than the Roylex YS. I have heard that the shoulders also extend up a little closer to the sheer line on the composite Wildfire than they do in the YS, but I haven't had the two close enough together to notice.
It should also be noted that there are composite versions of the Bell Yellowstone solo that share the differential rocker of the Royalex YS.
The first time I paddled a Royalex YS I didn't expect to like it a whole lot because I rather expected the differential rocker to make the stern "sticky" as I had experienced with the Argosy. I also expected it to be much slower than it turned out to be. Despite the fact that the YS has an inch less rocker in the back, it still has a bit more rocker than the Argosy does both front and back, both to my eye and by the manufacturer's specs. The shouldered tumblehome and elliptical water foot print of the YS also allows it to be healed over in a very stable and predicable fashion, so the stern hardly feels "skegged" to me.
If you look at the L/W ratios for the two boats, they are very close: just over 6.3 for the YS and just under 6.5 for the Argosy. But I think that the YS puts more of its overall length in the water than the Argosy does, so I suspect that in reality the functional L/W ratios are nearly identical. I suspect that the swede form hull shape of the Argosy gives it a slight straight ahead speed advantage on flat water, but for me it isn't noticeable, but the friendlier handling when maneuvering in current or waves of the YS definitely is.