I know what you mean, that's partly why I do most of mine in pencil, because I don't want to lose detail and I can get textures with pencil that I can't with coloured pencils. But I think it works both ways. There are details you gain by colouring a picture that just aren't there when they are only drawn with led pencil. I think you would do a really good job colouring this picture, so go for it! Also I'm quite interested in seeing what it would look like in colour.
If you're still worried though, maybe you should make a copy of your original picture first. I always do that for coloured pictures.

Wow, that's really great! I love all the detail. You did an awesome job. :)