Water-start is more difficult with cambers, no discussion about it.
Especially from size > 8m2.
It gets easier with the smaller sizes but remains more difficult.
I don't exactly know your windsurf level, but I can assure you that jibing should not be a factor to whithold you from cambered sails. Once you get used to it, you will actually prefer to jibe with cambers because they help you better pull through the maneuver. I'm talking normal jibes, no duck jibes or other fancy moves.
I only bring this up because you said yourself and I quote:
"I felt overpowered sometime and was overtaken by guys who are larger than me on a smaller setup"
Cambered sails help you a lot in overpowered conditions. The profile of these sails, creating the big belly, makes sure that the power of the sail stays in front which results in hammering the board down, discharging the load on your trailing arm. At the same time you'll benefit of higher and more controlled speed.
Perhaps you will benefit more from a better sail than from another board, although I agree that the IS97 is much better for your weight.
IS87 / IS101 / RRD114 / US147