I'm always amazed when people can do significant correction via the old-model PCs, at least in a timely manner.
I have two, and I've used them enough that both have been rebuilt, one of them twice. No matter what I used (and I did best with 4" pads, or 3" MF ones), it took *FOREVER* to remove significant marring, and I don't mean just an hour or so per panel.