I think this question may be off topic but are you also planning a higher bitrate test as well?
As you are no doubt aware, Quicktime Pro 6.2 has three quality levels at any given bitrate, "good", "better", and "best".
iTunes uses "good", and there is a significant difference betwen "good" and "best" at 128. Other reviews/tests I've seen have been comparing both. I would suggest testing both since iTunes has a high profile and QT Pro "best" has its evangelists.