Those rising peaks of errors used to be common on older 8X burners when they would get to the edge of the disc where it is much harder to control errors. With better media and 16X burners that would correct on the fly this has almost disappeared on quality media. I am not sure where Plextor is in this as I don't follow their burners much.
Also, I would avoid CMC mage01. CMC is trouble to begin with and I have seen some people with real problems using the mag stuff. With Verbatim and TY as low as they are there is no point in going to a lower grade. Even a very good burn on a mediocre dye could turn bad in the future.