It still works in Abyssea, even with merit abyssite. (The clicking HP trick)
I figured I would do a test with the
WHM ring, and yes they still do work. (Intervals of 10% Potency, ie Templar mace, Nobles, +2 head, Serp Set+AF3 Accessories[10%]) I didn't have to use them all, but I just wanted to see:
CureI, III, V with x1 10%
CureI, III, V with x2 10%
CureI, III, V with x2 10% - 1 Replaced With Ring
Switch off either 10% piece and replace with Ring
And so on, making sure that the Cure was the same/higher when replaced/introduced to the Ring. And yes, this held true!
Tested on a friend willing to nearly kill themselves D: