Hi there,
it would really be great if you could test one thing and report after that:
copy a file form your hdd which is attached to your AEBS to your mac over the wlan.
Through the copying process check with the iStatpro Widget if you notice breakdowns of the transfere rate like this:

(original thread with the whole information)
Apple sent me a new AEBS and I got still the same breakdowns and I really tried everything I can imagine to find the bug...
it would really be great if you could test one thing and report after that:
copy a file form your hdd which is attached to your AEBS to your mac over the wlan.
Through the copying process check with the iStatpro Widget if you notice breakdowns of the transfere rate like this:

(original thread with the whole information)
Apple sent me a new AEBS and I got still the same breakdowns and I really tried everything I can imagine to find the bug...