Okay, the thought wasn't more redundancy, but more throughput. Because, if the 10G link fails, I was hoping that the two standby become active. This would only drop our max speed by a fifth, not a tenth (single session still capped at 1G though, obviously).

If that isn't the case (because only one standby adapter is activated at a time), it makes no sense to have more than one standby adapter configured for each vSS.

This should be another story when using vDS, because there we can use LACP to team the adapters before assigning them a vSwitch.