Damage isn't necessarily instataneious according to what I've read. My understanding is in some cases you can use a flash with too much voltage for an extended period of time until one day... poof!
Originally Posted by anikin
Mecablitz 60 CT-4s are rated safe for recent Canon DSLRs. I've used one on a Canon DSLR, ETRS, and Rollei Integral. The amount of light a flash puts out has nothing to do with the trigger voltage. Far less powerful flashes than the mighty Mecablitz 60 CT-4 have baked cameras.
Originally Posted by Ghostman
Consult the chart in the OP. It is a great resource.