Periphery outer ring thoughts ?

There is a balance between the weight (mass) of the platter and the torque of the motor. On some tables adding mass to the platter with worsen wow and flutter. It does not matter how tough your bearing is adding mass will always speed up wear. If you have a suspended turntable it is a total non starter as you upset the balance and tuning of the system. Reflex camps are much easier to use than peripheral rings and press the entire surface of the record into the mat and not just the periphery. Vacuum remains the best. The compressors used are very reliable and quiet. The best system for the money is handily Sota's. 

Two problems. They are a PITA to use and prevent use of an auto lifter.
They have to be heavy to work and this will increase wear on the bearing and motor which has to work harder to get up to speed.
Vacuum hold down is the best followed by reflex clamping as used by Kuzma, SME and Sota. Sota sells a wonderful reflex clamp for much less than a periphery ring.