I've ridden Sectors since they first came out with version one. Three years later, there is finally some competition in the game (I guess North has the Freerace board, but it never seemed to catch on) with the RRD K-Free 60.
I got to ride it today and took a bunch of pictures. Full disclosure, we sell both Airush and RRD.
First, the dry observations. The outline is very similar to the Sector V2 and V3. There are some differences as the pictures show -- the tail is pinched more, the end is pointed, the nose is less full. The top deck is the bigger difference. The K-Free is almost entirely flat on top. The Sector V3 has more convex under the feet and a scalloped nose. On the bottom, the RRD K-Free has slight concave outboard. More toward the rails. Plus, the nose is absent of concave.
On the fins, the K-Free has a more surf shape and less of a race shape. The trailing edge of the RRD fins is scalloped and the Sectors are straight. The K-Free is only a three fin, mini-Tuttle set up.
The RRD straps have a huge amount of adjustment in them, the Airush has almost none. The RRD straps also cover less of your foot -- for me it allowed me to "elf" my toes more to turn the nose upwind while keeping the back foot flatter.
Whew, that is enough for one post. I'll put up the wet observations later.
The price is pretty much the same.