The lack of direct comparison between M80 & M60 is getting painful. Is there anyone in the SF bay area who has M60's? I have M80's we should get together and do a shootout, inquiring minds want to know.

Try this
http://www.goodsound.com/equipment/axiom_m60ti.htm
If you read till the end this article will give you a good idea of the differences.

The comparison has been discussed alot in the past.
The differences are quite small and primarily relate to the larger M80 cabinet, extra drivers. It plays louder and has a slightly greater bass extension.
I think in the A/B setup, one would be hard pressed to hear much else.