I am a Master Maine Guide for Sea Kayaking and work alone, with an outfitter, and race besides. I have owned a kevlar Isle au Haut for over two years. I honestly can say that I use it over most of my other boats or those that I have access to (Wilderness Systems, Current Designs, Hurricane).
It is easy to carry especially after a long paddle when you are tired. It follows a line easily and performs well whether using a regular touring paddle, a wing paddle, a bentshaft paddle, or a greenland style. The chines make it very stable (great for rescues of others). I don't weigh very much, yet I find that it tracks well regardless of wind, wave, and other conditions even without a rudder or skeg. Before I have to deal with weathercocking, others have lowered their rudders or deployed their skegs.
I have raced in it and found that it wasn't quite as fast as some of the 15' boats, and without a rudder very difficult to turn a quick hard hairpin turn needed sometimes in racing.
I would prefer to have a few of the extras found on the Eggamoggin (day hatch and special cockpit storage). My biggest complaint comes in the back band/rest assembly. It just doesn't work as installed or even changed. I would suggest that the rear of the coaming be lowered to allow easier greenland style rolls and to change the backband/rest to a different model and installation.I had heard from a local paddler that the Isle au Haut was a nice boat, but I was skeptical due to Lincoln's somewhat stodgy reputation. While working at a boat demo recently, I had the chance to jump into one and it was a real revelation. This is a NICE boat! It's stable, yet feels good on edge. It tracks well, but carves leaned turns nicely. It's roomy, comfortable and the thigh braces are well placed. It's also lighter than most comparably priced boats, due to its glass/Kevlar layup.
After bouncing around in it in 1-3' chop and 15-20 knot winds, I was left with the impression that this is a very capable sea kayak. Since my time in the boat was limited, I cannot speak to it's durability but I haven't heard of any problems with Lincoln boats. If I were in the market for a new boat, I would definitely give the Isle au Haut serious consideration. I'd say that it compares very favorably with the CD Gulfstream, which is a similar design. The only reason I'm only rating it an 8 is that I haven't spent enough time in it to give it a thorough test.
BTW, I also paddled the Eggimoggin briefly and it felt quite similar, but it has much higher volume.
For reference, I paddle a Nordkapp HM and also own a Walden Passage and a CD Slipstream (my girlfriend's boat). I've paddled at least 30 other models of sea kayak, mainly glass and wood designs.