I looked up the Dyo and it is specifically for oil based stains and adhesive. While it sounds amazing, I would be afraid to use it on vachetta that is relatively clean simply to bring it back to the new vachetta stage of color versus to remove oils from the handles, etc.
Yep, it sounds like the stuff would be best used for dark/dirty handles that have absorbed a ton of hand oils and dirt. Still, I think I may try it on my older vachetta...