I wouldn't say any of our current cats plane. They "lift at speed and reduce the amount of hull dragging in the water.

I sailed on supposed planning cat, the Planecat. On a smooth lake, it traveled through the water they way little fish do when a big fish is chasing them. It was noisy, it bounced, and it wouldn't track. To top it off we were outrun by a Hobie 16.

Opposite to this was a homebuilt 18 sq. It had very deep, very narrow hulls, with lots and lots of rocker. The idea was it had a great fineness ratio so it had a high theoretical top speed. The theory was as speed build, the leeward hull would lift, reduce drag, and go faster.

It was a nice boat to sail, smooth, good tracking and an OK boat to tack as long as your weight was aft. Actually it reminds me of the new Ventilo 16 with narrower, deeper hulls.