I did a small experiment today with my 10D, and hopefully can put this whole issue to bed once and for all. Anyone with a basic skill in electronic can repeat this test: All you need is an adjustable power supply with a current limit that can be fixed. The ISO-10330 calls for 30mA max for a typical strobe, but you don't need to set it this high (minimizing the risk of damaging the camera). Also the electronic switch in the sync terminal is open when the shutter is closed so there'll be no current flow at this time!
Slowly raise this voltage until it can't increase anymore, this is the onset of the protection circuit kicking in (and when the current started to flow). Now I know
(Metz knew) what this camera's limit is, exceeding the ISO standard by a wide margin. PM me if anyone wants to compare notes, but this leads me to only one conclusion: someone at Canon USA is ultra conservative (either that or their left arm did not talk to their right)!
The reason I did this experiment was I expected my 10D to clamp the Metz 45CT-5 output at 24V, but it did not since the camera's protection was set higher:
Someone at Canon did their homework and they deserve an A+ in my book