My gut instinct is that this won't work because most copper(I) salts won't dissolve in water without decomposition. Copper(I) compounds are strange beasts. They are very good reagents for certain reactions in organic chemistry where they seem to "carry" certain anions very well.
Originally Posted by Dracotype
Copper as a metal is certainly "more reactive" than silver as a metal, but we are concerned with the salts here. Besides, isn't the Vandyke reaction basically a Fe(II)->Fe(III) / Ag(I)->Ag(0) couple? (the initial Fe(II) being produced by photo-reduction of Fe(III) ammonium citrate) Maybe I'm getting mixed up here.