What does any of this debate have to do with a film suit though? Comic artists have it both ways when drawing batman. If he's shaded blue the one's who want to believe he's wearing blue can as can those who feel he's actually wearing black but with the animator shading it blue for impact.
On film there would be no leeway if batman is wearing a blue suit on film he is damn well wearing blue.
As well in all my readings of batman i have never heard the suit referred to by any one as blue or batman being referred to anything similar to the "big blue boyscout" or blue anything as superman is who is unquestionably wearing blue is.
I have however read him described as being draped in black in both dialogue and descriptions by artists/creators.
Also Alex Ross is famous for depicting the DC characters in their classic/traditional outfits his batman is always draped in black.