David,
As you recognize, more audio channels can be beneficial for VPOs, especially those which have been sampled dry. My experience has led me to believe that quality is more important than quantity. I presently use twelve HR824 monitors and also have eight of the MR5 which are tonally quite similar to the MR8. When comparing the HR with the MR, there is a fairly considerable difference in favor of the HR. Personally, I would prefer one pair of HR to six MR. The original pre-Mk II 824 is one of the best sounding and most accurate speakers available at any price. As an aside, I do all the voicing for the Paramount series with a single pair of HR monitors and a Trinity sub.
Joe Hardy
Paramount Organ Works