Well... I'm assuming you are talking about the new ones that just remove the stats from gear and leave the tier intact vs the old ones that remove the tier and items. The issue is that they effectively do the same thing since there is no way to put anything else on your tiered up wep or armor without dropping the tier back down.
However, the new Cleaning stones cost more. The only function of the new ones is that they make your T10 or T11 Wep look neat and pretty without the level 1 greens or banana stats. Other than that they are pointless?
The extraction stones, on the other hand, are very useful. The problem there is; 1. they don't stack and 2. they were available for, what, 4 days and never seen again with the new "make the sales special*" strategy....
* "special" = rare, short, and not particularly attractive... kinda like me!
-- Stagger - Osha - Eyeofthetempest --
M/R/W 72/52/51
Formerly M/D/S, M/R/D (The search for decent DPS in a post GCD RoM continues)