Pete,

I've built the Panache and the standard Guillemot, so can't comment directly on the Expedition Single. However, recognizing it's not the exact comparison you asked for, I will make it anyway. (Anyone feel free to correct my misconceptions). Forgive the stream-of-conciousness enumeration.

Panache: Very strong tracking. Very little weathercocking. Takes multiple boatlengths to turn, even with a paddle extension and boat lean. Bow rides over waves. Inspires a confident lean because of the amount of hull flare above the waterline. Near knife-edge stems require more twist to build than those of the Guillemot. Longer waterline and faster boat than the Guillemot (but maybe not Expedition Single). A bit more roomier than the Guillemot. The hatch construction is more complex and yields attractive (but raised) hatches. (of course, you can do a flush one too). The cockpit construction is different than the Guillemot (the Guillemot looks better and results in a slightly lower lip). The boat is built with forms raised above a strongback.

Guillemot: Weak tracking (again, not Expedition Single. However, I tried the Night Heron at the Rendezvous, and although it had noticibly better tracking, it didn't equal the Panache). Consequently, it's a joy to turn. Perfect for back-water exploration. Not quite as stable when leaned. Will require a skeg for high-wind paddling. Bow punches through waves as opposed to over (not surprising considering the volume difference). Easier to construct than the Panache because of fewer twists. Extra-cool looking cockpit with the recess (but I canibalized the lip construction method from that of the Panache). Flush hatches are the way to go to emphasize the beautiful lines. The boat is built with forms threaded over a boxbeam.

Having said all that, the majority of the construction methods are identical. If you can build one of them you can build the other.

There may be other intangibles that you might discern if you poke around my website. I've documented the construction of both boats. Feel free to email me if you want to pick my brain.

Good luck,

Ross