Well for those of you that had sleepless nights, I left patch-out in the barrel overnight again and now no more dirty patches. I was previously surprised at the black patch in what I thought was a clean bore the next day because I never experienced this with wipeout foam - I guess the patch-out really is stronger, or at least more penetrative.

As for using abrasives - I have used them for my entire shooting career and never had a problem. I certainly haven't noticed patches coming out black from a clean bore - either with gold medallion or copper cream - after a thorough cleaning, the worst I get is an off white/grey cream. I would still far rather use an abrasive than a brush, but thats just me (and a hell of a lot of match rifle and palma shooters I know). A few patches one direction with an abrasive to remove all fouling before patch-out versus vigorous scrubbing with a brush seems a no brainer to me and has worked perfectly for far better match rifle shots than I.

Thanks for the input everyone!