well you would want to get a cross over if you want to use it in small waves, low wind, but still get plenty of power when needed, and be able to release the power when needed, dont get a cam as you said, '
for me, i use a superfreak 5.8 for my ligth wind days, but im only 65kg, for my dad he uses a 6,3 superfreek.and his around 90kg the great thing about the superfreak is that, it is stable, great power, and lets the power out for bottom turns, etc, but what i love about it is that it is so stable you can rig it up for conditions like 13 knots and still be using it in 25 knotts, just dont want to water start. if you read my other posts on these sails it will become aparent im obsessed with them, but i think it more of the fact, they are the best, and i think if more people got on them they would last so much longer.
ok for the board sizes, in light wind i my prefrence of board for my 5.8 is a 100 ltre feestyle and for my dad on a 6.3 it is also the freestyle so i have to use it on a 85litre wave, but i dont like that board so i use it on my 69litre wave, with a oversized fin,.
a few things me and dad have noticed about these sails, the 6.3 can give the same power as his old 7.5 and still be stable, the 5.8 can give the same power as a 6.5 and still be stable, but whats better when the are rigged for power they are more stable than the 6.5 and 6.5 when rigged proply.
for me i like to much around with trying to get jumps i get dumped around on the sand bar, and these sails really will not break, so if you want a sail that will outlast your board, a super freek is the way
and also you can use this sail for freestyle, so thats a plus, but probaly want somthin like a 5,3 for that.

hope this is what you where after,
go to the
www.hotsailsmaui.com/ site and go have alook at the freak out forum all about the superfreek and everyones opinions on them