We did a bunch of mostly minor mods to the original design. I think that they mostly worked out:
Water tank location - Keeps the center of gravity lower and led to a minor galley reconfiguration that made it generally more useful.
Companionway step - I'm 6'3", 240lbs with size 14 feet (190cm, 110kg, shoe size 48 in euro) and the little chunk of wood on the centerboard case didn't look adequate. The step we did works great and is a fine place to stand while sailing.
Electrical "Closet" - We ended up with a considerably more complicated electrical system which largely stemmed from picking up an (apparent) bargain Torqeedo off of Ebay. We made an attempt at a solar electric auxiliary power but the Torqeedo first wussed out and then crapped out (replaced at least temporarily by a Mercury-branded Tohatsu 5 horse, can't afford the Torqeedo that would actually do the trick). Once the decision is made to to have an electrical system at all, it is easy to get carried away. We simply needed a place to house everything. Take note of the wiring run in the foam of the cabin top and the custom terminals for the solar panels.
Transom drains - I wasn't so keen on the sump and venturi bailer scheme so did a sort ramp thing on either side of the outboard well with using a cut-in-half PVC pipe to scuppers through the transom right at the waterline. My son was concerned that we would always have wet feet, but the only time any water comes in is with a whole bunch of people in the cockpit while at anchor, and not enough comes in to be a problem.
Lightning attenuation system - I don't know if this will work and I hope I never find out, but we sail in an area where thunderstorms come up quickly and can be hard to escape. The nature of this boat and it's materials make it somewhat problematic in a lightning strike. The carbon fiber mast conducts well enough to make it a target but not so well that it wouldn't explode sending nasty shrapnel everywhere. At the base of the mast, side flashes would be likely head toward the various water tanks, creating havoc on the way through and on the way out. I might be paranoid, but the materials and setup of this boat forced me to do something. What we did was to run a heavy gauge aluminum wire inside the mast (the type of wire used for terrestrial lightning rod systems) from an aluminum rod air terminal at the masthead to a beefy terminal on the cabin top. That connects to a big fat wire buried in the foam of the cabin top then to a run of aluminum bar stock that goes forward right over the top of the stem to an aluminum keel band that runs the length of the boat. This should both ground things well enough to keep static charges down and give the lightning an adequate path if we ever do get hit. This also gave us an opportunity to add some metal reinforcement to the centerboard pin but created the problem of needing a custom anchor light. My son's home made LED anchor light was an elegant solution (pictures attached). The only issue so far, besides having no idea if it will work, is that we should have tensioned that wire somehow as it bangs around inside of the mast while at anchor making a fairly annoying sound.
I'm sure we made some other departures from the straight and narrow but they are not coming to me right now. I know that the rigging is not entirely standard but my kid put that together and my knowledge is limited.
Jim