Ok here's what I found with my TTW outer ring.....
If you use ANY compressible platter mat on your turntable....it simply kills the dynamics. The 'air', transparency and 'life' of the recorded performance is simply suffocated.
It does however flatten warped records 😎
If conversely you use no platter mat but place the record directly on the platter (or use a solid metal platter mat)....the outer ring tends not to then rob you of those vital ephemeral nuances.
As I have but two or three discs warped badly enough to warrant 'flattening.....the ring is rarely utilised.