Summary

Pointers at the tops of my RigidBot Z rods tell me right away if the rods get out of sync. I had a lot of problems with this at first until I got everything tuned... Since then, I occasionally do something stupd which causes them to get out of sync.

Install 2 and point them in the the same direction when everything is aligned and level.
Many thanks to mike_linus for NutJob http://www.thingiverse.com/thing:193647 upon which this is based.