Hmmm, I don't have an answer for you! I'm only posting because, however impractical, it is a rather fascinating idea!

It would also be fairly hard to do. At least in the sense of creating an atmosphere where one could walk around the room without getting the glare in their eyes. Also getting enough light might be a problem. I imagine most 'next to a window' light source situations would be hard for a banana on the long term- but I could be wrong. And then you would only be 'catching' a little of the window light... And there would be degradation along the path.

When it comes down to it, I don't think you will get a better answer than this: Try and see.

Lol, I guess I had a few answers after all.

How about a gro-light instead?

I've done a lot of reading about what to put on walls to increase the effectiveness of high intensity grow lights. The experiments I read showed that mirrors actually absorb a lot of the light. A shiny white plastic was best, although not very pretty.

I think the light rays are whats important here. With mirrors you are only going to get the reflection of a light ray and not all the goodies that come with it, ie heat, color, temp, radiation, etc....