Here is a link to a test of the Little Wing 18 in a Norwegian magazine: http://www.scandickajakk.com.
During the test they found the top speed was 7 knots and the cruising speed was 4.8 knots. I paddle a Little Wing 12.5, and I would agree with your comments that. "it seems to have just made the boat more stable while maintaining good speed and not really have reduced drag... looks really nice though..". The 36-Lb weight is not bad either for an 18-footer. I would agree that there may be better boats for your purposes.
Hey, Thanks for your comments....
.... you've made a comment about weight, from what I've come to understand about boat hulls, weight isn't as important as it may seem in terms of speed. In particular, Kayaks weighing 10-15 lbs apart will not improve overall speed, though it will carry less momentum and seem to take off quicker I suppose. I could go into the science of it but basically it's about the wetted surface not changing all that much to make a serious difference.
In terms of speed, 7 knots is quite good I suppose, I'm a beginner who has some upper body strength and found that I could push my P&H only 6knots for any extended period of time. Though i wonder about my Kayak's ability because it was so easy to use a slower speeds (usually indicating a different cruising hull style)...
Would be interesting to see how the Little Wing 18 could do..