Any problems or complaints about these discs?
Memorex are constantly changing manufacturer.
As for prodisc, I never have problems with them, but there are reports of varying quality.
When I bought a spindle of Memorex 48x made by Prodisc that was the first time I bought CD-Rs from Prodisc. I probably won't buy Prodisc CD-Rs again. I get C2 errors on these often on my 52246S.
Are all Memorex 48X CDRs made by ProDisc?
They're tested in the media test thread. The answer to your question is no, they're not all the same.
ProDisc Memorex 48x