Re the I17... Why hassle with the boards coming in and out. Any sand upwash and the board could get stuck etc etc. No boards on the tramp to worry about when you storm onto the beach. A mistake with the boards is expensive.... If you are not racing. I would think the 5.0 with a chute would be a good solution... Same hull construction as the 17 with less aggravation. Wouter has noted that it's gaining in popularity in Holland... same purpose that you plan for it.

Anything other then the TheMightyHobie18 will require attention to the bottoms yearly.

Mystere used a metal strip to protect the skegs of their 5.0 (same as the Nacra 5.0) so that could help you out on the wear and tear issue.