if the Revo had a switch to turn it off and could charge accessories, I would probably build up an SP dynamo front wheel.
I remember looking at that light when I was considering one for mountain biking, and how odd/annoying it was that they left off an on/off switch. Seemed like a nice mtn biking light otherwise. Not sure if it would work well on the road - mtn bike lights tend to be designed to put light where you don't need it. Not just the cutoff, but you have more trouble getting the throw down the road you need.
Paul, you explained it well. The color on a lot of these dynamo lights is hot. I find it annoying and fatiguing when these lights are behind me.
I would include many of the battery lights I've used in that as well, but otherwise I agree. I'd really like to see more lights with color temp / light output.
I am not in love with the Fenix BT20 but it lasts a long time (full night) and provides a good throw. It meets my needs. I am hopeful a Revo Mk2 comes along (it puts out a ton of light) remedying the two above fatal limitations.
I'm not personally trying to talk you into a dynamo. Certainly a dynamo is never going to put out as much like as a 800 lumen light with nice color output.
I do hope we'll see dynamo lights with better color output this year though...