Ive got the vented 3racing one. I lathed it and polished it , it seems to work great. Either way the stock unit should also work well , I really cant see any problems from it braking wise. Very solid. If your looking to drop weight , shafts are better choice. But it is another item to further lighten drivetrain.
Also remember a vented unit will wear down the pad faster. It will allow gases to pass freely during venting and it should help cool itself due to the higher surface area the slots create as well as being able to pass air through those ducts when spinning.
But for the price of the kawahara , its really not needed. Id say you can spend money elsewhere on more beneficial things. I got the 3racing cause its cheap and does what I need.
Kawahara is a no brainer , it seems to be the best for everything , especially at draining the wallet.