We've chartered the Sunsail 384 and Moorings 3900 which is pretty much the sail version of that boat. Can't comment on speed as that clear is different.

The two times we've been on it, there were 2 of us and then 4 of us. Worked great for 4 with each couple having their own hull. With 2 of the 6 being kids, you should have plenty of space.

I find things are a little tight when working on meals..etc but you have plenty of room to spread out otherwise, especially with the flybridge. Cabins are comfortable too. Also plenty of fridge and freezer space.