A few years ago cmc magenitcs where not the best disc maqnufacturer. I think the variations in quality may have been due to the fact that it was made in all sorts off small spin off factories all over the world (which used older lines from their factory in taiwan.) Mexico, UK (newcastle) and Ireland. They have recently closed these factories and have maintained 2 one in china (cd-r) and the DVD factory in Taiwan.
In recent months a lot of Tier 1 brand names have switched volume orders over to CMC so their quality has no doubt improved.
As of the Datasafe CMCMAG i have no idea. Datasafe is generally supposed to be a higher grade than Datawrite. I would give these a whirl and report back with the results.
Flash has done a number of tests on dvd-recordable (please note dvd-rec is a datasafe sponsered website so the results may be biased) on the cmc mag discs and they seem to be ok.