My Nucore RFM (with a computer I built) has been running extremely well. I've got over 700 games on it since the Nucore installation, and about all I can report negatively is that twice the entire machine reset during Martian Bowling (which is a known bug in the RFM code, not a Nucore problem). Supposedly that was fixed before 1.6, but I'm running 1.6 and it has happened to me, although only twice in 700+ games. Apparently, that bug was not totally squashed by the P2K team before they got their walking papers.
Other than that, the only thing I've noticed is that the sound sometimes starts to break up during Mothership Multiball. The sound never has any problems in any other mode, and it isn't terrible during Mothership Multiball (in fact sometimes it sounds perfect through the whole mode), but often it does start to break up. Almost like there is just too much audio going on at the same time.
Just wondering if this is a common RFM problem regardless of the PC's 'horsepower', or if perhaps an upgrade to my hardware could make this better? I'm not sure I'd plunk down the cash for a new motherboard and/or CPU just to fix this since it does not affect game play or anything, but I was thinking about picking up a spare motherboard anyways at some point, fearing that the 'integrated parallel port' might go the way of the dodo bird.