Totally agree with this post, I had bought 10 of these discs and tried them on a multitude of burners, many simply spat the disc out or failed part-way through the write. As you say C1 errors were sky high.
After emails to Memorex I managed to them to replace the discs with 10 DVD+R (CMC) to cover my postage - they admitted there were compatility issues with the discs. Although I challenged him to advise me of a drive they would produce acceptable results in and they couldn't!
I now use 700mb 24x or 32x verbatim cd-rw, and I also have good results with TDK 12x.