If you have low-rise bars and have a problem with hitting your plastics when you turn a +1 or +2 would help. Alot of people just stick with the +1. I've seen people with +2 also. It's all in what you like.
My rolldesign +1 has antivibe mounts, the bolts that stick thru to mount clamp rubs on the plastic. They could be trimed back a bit since the bolt sticks thru the nut some, trimed it would be enough to clear the plastic. The rub is only a small amount at full lock. The antivibe does seem to make a difference.
Other than that the splines fit great and the fit and finish is excelent.