Tron,
I've heard, but not been able to confirm, that the WAP11 only uses on antenna for TX. (I was told the left, as you face the unit.) The diversity should only work on the RX anyway, assuming that the design engineers were worried about multipath back to the unit. You don't worry about multipath on TX, as it is a reception problem. Would that explain the activity you saw?

BTW, I'm not arguing with your results, I'm trying to figure this out, too! Also, did you try to explictly change the antennae through the software? The WAP11 Configuration software lets you set them manually. I'm just wondering if you would have seen a signal change if you'd switched it via the software, vs. trying to let the diversity switch make the decision for you.

Cheers,
Thorn