Lenneth,
Interesting reading, but I get the feeling it's fairly biased toward "let 'em all hang out"!! I remember some of the girls of the "burn the bra" movement, and it wasn't pretty!! It depends a lot on breast size and weight, types and duration of physical activities, etc.
Say what one will, I have never found breasts that level off at about the lower level of the ribcage to be very attractive. One thing that every site that mentions drooping or sagging will agree on is that it is irreversible. Surgery will help, but not completely restore it.
I'm also not sure just how much of this would apply to us "fellas", as the only coopers ligament we have is below and behind a much lower-located appendage. Does this mean that with comparably sized breasts a male would sag faster or slower than a female?
Just curious. For the time being, I believe I'll keep wearing one as often as I can. Passing the pencil test doesn't just mean one has nice sized boobs, it also indicates a bit of sag. But, maybe we actually have better support muscles??