I had my Sunpak PZ5000AF lock up my EOS 5 on many occasions in TTL mode. I never, not even once, had an issue with it on my Elan 7e. In auto-thyristor mode with my 10D, the flash will sometimes kick itself back into TTL and since the DSLRs lack the circuitry for TTL flash metering it will fire at full-power. These days I mainly use these off-camera, in manual mode and externally powered, with Pocket Wizards. A pair make a decent mobile kit.
