I had mine converted over a few months back since I smoked a new belt after only 30 minutes of use with the new clutches. The bearing has no impact on engine braking because the diameter of the bearing is too small (= less surface area) to hold the belt and keep it from slipping when the clutches disengage as compared to the stock primary. So basically the one-way bearing buys you nothing and adds a higher probability of smoking the underside of your belt if you coast down hills with the clutches disengaged. With the 2-way bearing, you can coast down hills and the bearing will spin and will not have the potential to slip and burn up your belt.
I will add that I don't make this a common practice because even though the bearing does spin, it is spinning rather fast and does start to whine pretty loud if you get going too fast. But since the change, I have had zero issues with my belt and no noticable difference in the engine braking.