I've heard nothing but good reivews on scotts dampners. I was in the market for one, you bet your a$$ it'd be a scotts. The lowest I've ever seen one sell for was $375. I've talked to people who have paid as much as $550 for them.
I have one on my r6 and like it worth the money but on your f4i I don't think you need it I trade with my buddie all the time and it handles great not many tank slappers try to dial your bike in before you spend $400 and see the differance just my $.02