I had the Minolta Color Meter III, and used it for several years. When I bought the Sekonic L758DR exposure meter, I wanted to match the RF trigger function in it ... ergo, the Sekonic C500R.
I frequently shoot at night with my herd of twelve Nikon SB800 speedlights in full manual mode, and the RF trigger in both meters is very useful.
The C500R has two red sensors in it: One matched to the film emulsion sensitivities, and the other matched to the human eye and digital camera sensitivities. The Film sensor recognizes three fairly sharp, distinct peaks, one for red, green, and blue, with very little overlap. The human eye/digital camera sensor matches the human eye red. green, and blue, response curves, as do digital cameras, which includes a slight blue sensitivity (about 30 percent) in the red portion of the visible light spectrum, and greater overlap than the film sensor.
I also like the consistency in their design: control layout, display, size, etc.
I hope this answers your question.
HBB in Phoenix, Arizona Nikonian Team Member
Photography is a journey with no conceivable destination.