There I was trying to decide between #9 or #82 to follow #83 and a load of you rave about #80! I still can't determine what the difference between #9 and #82 is...
#82 is newer, and made more for machine application. It is supposedly slightly more aggressive than #9. If you want to use hand-application, and maybe prefer the smaller 16 oz. commitment or ease of finding it, get #9. If you like the larger 32 oz size, and finding it is no issue, or you plan more to use PC/rotary/etc, then get #82. From what I understand, the difference is not large.