I used a synthetic in my 750 and braking is very strong, well at least as strong as a single puck caliper can be. I still have the original brake line I think. It is rubber anyways. I want to get a braided but I have too much other stuff I want to tinker with to afford it right now, maybe over the winter.
i dont think fluid type matters as much as making sure the system is in good working order. It does not matter what fluid you get or how often you flush if you have worn parts. Both must be in good order.