I'm just in the process of upgrading my sails but after reading some reviews on the 4 batten sails i have been getting the feeling they are designed more for a lighter sailor. I tip the scales at around 96kg and normally sail with a 0.5m bigger sail then anyone else on the beach.
I'm way too heavy aswell 
i've sailed a few 4 batten sails, the only prob i found with them is the tend to rig on smaller mast sooner, like a 370 on a 4.7m, where as my 370 don't come out until it's 4.2m weather.
So being heavier and the mast softer makes the sail a bit spongy and loses its shape a little.
The do feel sick on waves though..
I rig my 4.8 on a 400 ( which I cut a few cms off) as opposed to the recommended 370 which I find too soft for the 4.8. A way around that particular problem.
