I have made some scans with my 3540A of several media I have BURNED with my 4550A. The firmware I used was 1.06bt rpc-1, available at http://liggydee.cdfreaks.com/page/4550/.
First one is a Ritek G04 @4X, branded RiData, I hope liggy/dee will provide us some speedhacks for this quality media.
Next one is the Ritek G05@8X, branded TraxData, also very good media. My guess is that this same strategy can be used on the Ritek G05 using the MediaCodeSpeedEdit:
Seems like the 4550 supports this nice tool, I will try it myself :).
Third scan is an unbranded OPTODISR008 @8X, not very good, although no problems reading it back and low PIF.
Last one is Nashua branded AML001 @4X, stay away from this crappy media.