1. It's impossible to say which one is of better write quality. Speed graphs prove very little in this regard. All we can say that it appears all of the above three scans may have been somewhat problematic for the reading Pioneer drive.
2. Pioneer drives can report c1/c2 errors (can't vouch for accuracy yet, haven't tested enough):
3. Mitsui media is these days MAM-E / MAM-A media. Not all MAM-A discs are bad in quality. Their Gold archival cd-r discs are very good (NIST 10/2004).