Your choice, obviously.
Mine has been used for Meg's #9 since October of 2002. Seems to work fine as a polishing pad. Just a little more effort to use the screw-on pad, but no biggie.
Good questin. I wondered about that too. This is good to know. Like you said Charles, a little more effort, but shoot, I can deal with that in order to have one more pad. I just didn't know what to equate it to - cutting, polishing or finishing or none of the above.
I used mine a couple times with Meg's #9, then threw it away. It seemed to be prone to flinging product around, and I got tired of cleaning up all the splatter.