Steve,
I have a Nacra 5.5SL. In short, I think its a great boat. I do take my family on it (wife, kids 8 & 4) but would not consider it to be a family boat. It was designed as a racer so has quite a bit of complexity. That said you can ignore most of the finer settings and it will work just fine. The wire across the tramp will get in the way. I removed mine - details at nacramania.com. The boards could be an issue if the lakes are shallow or rocky. But it is boomless which is good with a lot on board. Most parts are pretty standard and available at murrays.com (or the catsailor.com store!). The manufacture (performancecat.com) has big ticket items if needed as I think it's still in (limited) production. Re-righting is pretty normal and will take 2 persons without some other aid such as a righting poll. I can't compare it to the Prindle 18-2 but from what I have heard and seen, the Prindles were OK boats.