I've finally decided to order the NIkon SU-800 Wireless Speedlight Commander. I'm buying it to enable wireless-TTL control over my off-camera, SB-800 Speedlight, without having to fire an on-camera flash. I currently own an SB-800 and an SB-600 (plus, a pile of "dumb" Vivitar 283s with VariPower modules). In the past, I've used cheap, $10 optical slaves to trigger all of my my "dumb" flashes, and I seem to remember that they didn't work well in broad daylight.
I know the SU-800 operates on IR. The photos I'm planning to shoot with the SU-800 will primarily be at magic-hour (the 20-minute period, just after the sun sets), so the ambient daylight should be fairly subdued.
My plan is to mount the SU-800 on my Nikon body's hot shoe, and have my SB-800 Speedlight mounted on a 40" extension arm, clamped to a Matthews Foamcore holder, with a 4' x 4' piece of Foamcore attached. This rig will be handheld by an assistant. The assistant will be about 20'-30' from my shooting position, with a clear line-of-sight to the SU-800. Apparently, the SU-800 also supports the SB-600, so I'll probably put that on a stand, on a separate channel-group, and use it as a three-quarter kick, also with a clear line-of-sight to the SU-800. This is all on location, outside.
I don't expect a problem at dusk, but I was wondering how well the SU-800's IR works in bright daylight. If anyone here owns an SU-800, and has tried it in bright daylight, how does it perform?