We've been looking for a more intelligent mechanism to bond ethernet connections in a primary/backup configuration using latency, packet loss and jitter characteristics of the loops/tunnels involved.

Say you have a RB750 at a customer prem and have two different upstream providers. There's a EoIP tunnel provisioned from the RB750 through each upstream to a terminating RB1100AHx2 type device.
The two EoIP tunnels are provisioned in a primary/backup configuration, however the additional metric(s) of latency, jitter and packet loss across each EoIP tunnel can be used to determine if/when the choice is made to switch from the primary provider to the backup provider.

Many times we deal with degraded performance issues as opposed to simple up/down scenarios. Having some way to cope with these types of issues automatically would be very beneficial.