Digital BW, The Print

How quickly do OBAs wear out in a print, assuming a brightly lit room, 
but not with direct sunlight?� There is probably a huge range, of 
course, but some papers, such as Red River Polar Matte make excellent 
and quite neutral prints with a carbon inkset, along with a very good 
dmax.� Sure, for really expensive prints, I'll use Epson Hot Press 
Natural or similar, but using something like Polar Matte would be a nice 
option for lower-priced prints. If there's a noticeable change in a few 
months, well, that'd be a problem.� But if we're talking years, then it 
wouldn't be.� After all, don't most photo gelatin papers contain optical 
brighteners?