Configuration Help- BENQ DW1640 or Liteon iHAS422-08 as reader or writer?

My Liteon SOHD 16P9SV was running slow (even after u/g’ing firmware) and was giving me quite a few read errors— so, I upgraded to a new Liteon iHAS422-08 (SATA) - teaming it with my existing BENQ DW1640 (IDE) drive.

My question is this: Which one should I use as the reader (/ writer)?

Right now, I am using any/ clonedvd/ dl dvd’s, with the iHAS422 as the reader and the BenQ as the writer (BenQ has historically handled DL discs decently)- and the setup seems to be working- but, I would like to optimize if there is a better way to set things up.