Robin,
I have not had time to test this, but the documentation states that it can be done with some of the other mode=x numbers, where the mode number represents different types of bonding ie. round robin, active/standby, etc..
Let us know which mode you go with.
I'm reading the bonding doc, i'll give a try to the active/active mode, just nedd to make shore that bonding emultates only one MAC addr. Need also to understand if the switch needs to deliver a trunk or just a usual port to my box.
I'll come back later with me config.
Thanks,
Nassri