I use three FL-600R flashes and they are GREAT! The only time I have a problem is when I need to fire a large off camera flash (Photogenic 320B) and still fire the FL600R while on the camera. I bought a radio transmitter that mounts into the OM5 hot shoe. The Olympus flash then mounts into the hot shoe on top of the transmitter. this piggyback is not as unwieldy as it sounds. The problem is that the camera has to be in manual and the FL600R should be in auto. Unfortunately, the FL600R will not fire in auto with this arrangement. My older FL50 flashes will fire in AUTO on camera or off camera. I really like the size and weight of the FL600R but this is a big drawback. I could go back to an old photo slave but there are too many competing flashes at special events. Ideas?