I can live without load balancing (though I would think that once the one link was saturated, packets from another source would go over the ethernet connection in the vif).

In most circumstances it should load balance, but the algorithm used by the switch actually doesn't attempt to "load balance" per se; it simply distributes traffic across the links based on the source and destination address of the incoming packet. In other words, the switch doesn't pay attention to the "load" on each link. By using a simple hash function on the incoming packets it distributes them over the available links; if the packets vary in such a way that the hash function distributes them fairly evenly, the load on each link on each link should be roughly equal.

Sam