Ed, water is just about the very worst thing you can use on any lens. First of all, the lens surface will be hydrophobic, so water will not spread evenly, and moreover the [inevitable] contaminants in the water will immediately precipitate out onto the lens. Also, some of the AR coatings make this issue even more important. Finally, the most deleterious substance on your lens would be oil, against which water will do no good at all. If you must use water then you must also add surfactant or you will probably make matters worse.
That's why geek optics folks like me use spectral grade MeOH or EtOH with as much water removed as possible
Since I am already being a contrarian in this post, permit me to also disagree with your assessment that a damaged Leicablad lens is the saddest sight in all of photography. To me the saddest sight in all of photography is a fantastic lens with a UV filter on it. IMHO a person who is willing to pay the bucks for fantastic lens should also be willing to take the risk of letting the lens do what it can, in all its naked splendour.... as the lens engineers (and indeed, God Himself) intended for it to be used.
I will now dismount my soapbox