Magnus, I don't (personally) worry about that stuff. There have been several discussions under the "growing under lights" forum discussing this. As I recommended to the original poster, I recommend "full spectrum" as did you. While it may seem wasteful to some folks to provide more than the plant actually requires, the red/blue solution looks weird to me. All of my lights are either full spectrum (CF) bulbs or a balance of t5 straight tubes mixed to provide a K balance of approx 5000Kelvin. This is because the Kelvin reading of full sun at the equator on a clear day is approx 5000K (actually about 5500K) and most "daylight" films are color balanced for 5000K. I personally like the color rendition at 5000K - just my opinion. Good response Magnus. Here's a few links to get you started.
Affect of artificial light on Orchids
My first LED array is here...
Relying solely on lights - advice for my next setup?
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Ross
http://orchids-ross.blogspot.com/
I don't do most Dendros or large, "floofy orchids". For me it's minis (like Angraecoides), Masdies, Paphs, and others that crept in somewhere along the line. See my orchid list for complete collection (usually not current.)