You have not stated the version number the DVD-X-Copy that your friend is using, so none of us are sure what you mean by “old”. But I’m suprised that your friend can be both a newbie and also truly be using the “old” DVD-X-Copy because it has not been available for sale for over two years. Even if your friend did get a hold of the “original” DXC, installation requires activation from a company that has less than a sterling reputation and will hit you up for a sizable chunk of money. Most of us old-time original-DXC v.1.5.2 users are still running on an HDD installation that is 2-3 years old. As Gurm pointed out, depending on the version of DXC and your configuration, some systems do experience conflicts but many, like your friend, experience good results.
So, I’d summarize that, as you noticed, DXC is simple and produces good quality but it is no longer available and I would not pursue trying to get it because the current “new” DXC products, in the opinion of many, are not well engineered and even if you got a hold of the original DXC, it would involve paying out $100 to activate it or obtaining a crack which means visiting dangerous websites. And we are not allowed to give you support or help for cracked software.
In short, don’t fret that you don’t have DXC.
In my humble opinion, your dollars have been well spent on the CloneDVD/AnyDVD combination. CloneDVD or Shrink is a much better product than DXC Express or DXC Platinum for compressing a DVD9 original to a DVD5 backup disk. So you already own your compression solution. And if you want to keep 100% quality, CloneDVD also splits an original over two backup disks and CloneDVD (with some limitations) and DVDDecrypter/ImgBurn also burn to dual layer media.