I don't think it would actually lighten the color. To the best of my understanding, if you took a breeding pair of black birds with recessive white, a portion of the offspring would be black while some would be white. Blue in general is a dilution of black already, but I do not think the...
I would save a splash myself.
Here's what white roo over black hen gives...
Here's white roo over blue hen...
Here's splash roo over white hen...
I agree with @igorsMistress though, and would consider other factors before colors. A mean rooster can be as beautiful as a nice rooster, but...