My understanding of TTL is that a pre-flash is sent out, the camera meters the scene and then automagically sets the flash appropriately. RC doesn't rely on this at all, does it? If I want to remotely command multiple FL-600R via radio rather than optical, and am happy to forgo TTL functionality then it's a non-issue, yeah? Or does the radio being used need to support TTL for RC to work? RadioPopper PX system (http://www.radiopopper.com/#!px/c18on) looks nifty. Works as a bridge. Doesn't state Olympus compatibility but may not be an issue. Everything else I've seen in the way of PocketWizards, Apurture, Cactus...leads me to believe they will only act as a trigger. There's not remote capability and you have to individually set the flashes which won't always be possible if they're strung up somewhere inconvenient.