You can google this issue but I think you will find "most" sites say that once a disk is burned and playable, it doesn't matter what the recording speed was. After that, regardless of speed used, NO DISK--even pressed ones---are readable by all players. You should find that Plus DVD disks seem to have a higher percentage of readability but again no guarantee.
I had one CD that would not play in the burner that made it but played just fine in my friends computer---so never throw a bad disk out. Somebody might be able to play it!