Snowboard Flex of 6 too much for a beginner-intermediate?

I've only gone snowboarding for 6 days total,and I'd say that I'm a pretty decent snowboarder. I have a grasp of carving and can link turns and speed down the slopes. Does anyone know how stiff rental boards are compared to the one I am looking at? I'm eyeing this snowboard with a flex of 6....Will it become too stiff for me?