I use 1 on my 10x42 ELs. It's wonderful for use as a light weight carry bino and spotter all in one. The doubler reduces the field of view quite a bit, but I already have in site what I want to look at anyway so it's no big deal to me. However the color fazing drops off considerably as well when using it (colors aren't as brilliant). But again, I already have in site whats needed when I use it. For a light weight mountain or climbing set up, it's hard to beat. Mine will always have a place with me.
