Sorry, I just saw this post today.
Very complex question.
First, the IV-P's wingloading, and pretty much all the Lancair designs is high because high-wingloading typically means low drag in low AoA (i.e. cruise) conditions. You reduce the wing area to the minimum required to give you the type of stall speed you want or can live with. The parasitic drag at high speed cruise is minimized, and since you're looking at low AoA in cruise, you don't create too much induced drag as a result of the higher wing loading. So, in my opinion, high wing-loading is good. Look at the Nemesis NXT for proof of this. The bad part is that stall speeds and low-speed handling begin to suffer when wing-loading is high. A lot of manufacturer's don't want to manufacture "hot" aircraft because they will lead to higher accident rates, higher insurance costs, and ultimately a bad reputation. My plane, the Grumman AA-1 is proof positive of this. It was designed as a trainer that would actually make people learn some stick and rudder skills. It was fast, high-tech for the time, not very stable (i.e. quick maneuverability), laminar flow airfoil, etc. As a result, it took higher skills to fly properly and after a series of low-altitude stall/spin accidents from ham-fisted student pilots, it gained a reputation as a killer and difficult aircraft to fly. The Aerostar is another good example. So, in order to lower wing-loading and thus, stall speed in order to meet FAA certification, Cirrus chose a higher drag wing design, that doesn't offer the same performance, but is more benign. Lancair, since it didn't have to make the designs conform to FAA certification number exactly, didn't have to do that. One interesting thing to note is the difference in planform between the Lancair IV and the Columbia/Cessna 350 and 400. On the certified aircraft, they change the wing chord out near the tip to improve the low speed performance of the plane.
Now, I'll caveat this all by saying that I'm a semi-educated observer and that I think the Lancair line of aircraft are probably as high-tech a kit plane as you can buy in that class. If I had the money, its what I would buy, unless Epic started making something smaller. But, they do have some things that I don't like. Ultimately, I can't really answer your last question. Without some serious time invested, any answer I give would be a SWAG that I pulled out of my butt. One short description of the planform would be that it would probably be something like 8 Aspect Ratio with .45 Taper Ratio, winglets, no wash-out, and a Riblett GA 40-215 airfoil. That's probably about the same as the Evolution wing, albeit with a different airfoil.
