I don't think this is an appropriate question for these boards..but hey, I'll try and answer.
About a year ago I was unfortunate enough to recieve a large number of CDr games for NGCD, with a system on eBay. Had I known they were CDR I would not have bought them.
I have a Top Loader system, and it will play some backups fine. But pretty much any fighting game, or newer game will crash after about 15 minutes of playtime, and give an i/o error.
Some times instead of an i/o error I would get a screen saying "this is not an offical SNK product please buy the real game" or something to that effect.
I have heard that the CDZ will not play them at all...but I do not know from expereience.
So in short...the NGCD will play backups of a few games without problems, but the majority of them it will not play...or at least mine will not.
And finally...NGCD games are cheap as shit man...why not just buy them?