The weights on the Alexrims site are likely without spokes and hubs since they literally just sell the rims. Any Alexrims you buy have hubs from Formula, or some other manufacturer. Easton sells complete wheelsets.

As for performance increase I upgraded from a similar set (alexrims DA22 )to Fulcrum Racing 5 which are very similar in weight and design to the Vistas and its like night and day. The Alexrims suck, I knocked them out of true multiple times on not major bumps (a friend has Alexrims A400s that bend often too) , meanwhile the Fulcurms have been prettymuch bomb proof (and I took a couple hard hits with them!). Not only that on your first ride you can feel the faster acceleration significantly, and IMO while cruising it feels like less effort is needed to maintian the same speed.