I will be installing 5" Bruce flooring over a 2x6 t&g sub-floor. Bruce says it needs to be glued down, however, other manufacturers are OK with stapling 5" planks. I am living in the house and don't care to mess with the fumes from the glue. The floor will be installed on the second floor. I will be installing 1200 feet.

There is a reason for the gluedown only. The manufacturer has tested all installation methods, and all the others failed.

Your going to need plywood subfloor either way, according to Bruces other wood that can be stapled.