Both of those methods have the possibility of being very aggressive while cleaning that particular style of foam.
That coupled with the "sticky", and stubborn consistency of the polish can lead to hastened wear from trying to get them perfectly clean.
I've killed a few pads early on with that pad conditioning brush by trying to get them really clean, when I only needed to "knock" the gunk off.
I clean UHS pads by hand, and find the polish resistant to any cleaner I have on hand.
My experience using grit guards to aide in cleaning pads has me coming away feeling that while they work great for traditional foam, wool and microfiber pads, I would probably not want to use it to clean blue, green, or grey Rupes pads. The unique consistency and cell structure of these pads makes them more sensitive in their use and care.