This was discussed a few days ago in a thread that dropped off.)
Desired setup at events where pre-setting flashes is possible:
Two *manual* lights high up in the "back" corners of the space high enough to paint the key areas. Radio triggers. My camera has one on-camera strobe operating in ETTL mode to fill in faces, moments not fully lit by the light coming from the "back". That light I measure in advance so know the fall off and amounts in various places around the room. This fixed lighting might at times be seen as sidelighting as I move back and forth during the event, but as the photographer I KNOW there will always be at least rim lighting. The intention is that this manual lighting will in most cases be brighter than what comes from the camera-mounted strobe as fill light.
OK, I used to do this stuff without ETTL gear. Annual reports, location stuff of all kinds. Parties, too. (fun!)
Flash-forward to current day rigs. I see the complexity of the possible answers: The timing of the flash is different. I am assuming that there will be no HSS, but it might still introduce different delays. And then maybe HSS would be needed if the event were outdoors.
But back to the ETTL issue: Can ETTL just worry about its exposure/distance calculation without allowing the brighter light to freak it out?
I am planning to buy several more modern speedlights either Canon or YongNuo to add to a motley assortment of Vivitar 285's, a Canon 580EX(not v2) and Norman-hulking-mega-Watt-second power pack or two (not used very much these days!) so I can do more events, editorial and help with my existing real estate work. New and old units will end up sometimes in softboxes, umbrellas (yuk but convenient) bouncing off ceilings. You know: the whole weird Mcgyver thing-whatever works.
So, can modern ETTL operate in this kind of mixed strobe environment? Have to all be the same brand while still set for manual and ETTL? Or free-for-all?
Thanks for suggestions...