The camber induced Element sail will be slightly heavier, yes, but having the draft in the sail "locked in" by camber inducers may give you significantly better performance, especially in winds < 13 knots.
I would suggest an 8.5 m2 sail if you have the skills.
You need to try out an 8.5 m2 first.
Borrow one at the beach for a few minutes if you have to.
Hope this helps,