OK, so I figured out an easy way to copy SDK, which is weird but fast and easy.
- Disconnect the joints from the body.
- Group it with it's controllers.
- Duplicate Special the Group with duplicate input graph checked.
- Set the new duplicated group's scaleX to -1.
- re-attach joints to the body.
you end up with a transform group null, but besides that, it mirrors perfectly with SDKs and everything.
Maybe they fixed the 'copy SDK' in bonus tools in 2014, but the one in 2012 doesn't work very well.
Thanks again!