low end floorstander or high end bookshelf?

i'm currently running a pair of b&w 683 floorstanders with a large velodyne hgs-18 sub. would a better quality bookshelf like a b&w 805 diamond with the same sub be an upgrade? i've heard that even with a sub, the bookshelf doesnt sound quite as "full" as a floorstander with the sub.

im about 50/50 music and home theater. i'm more critical of the music tho. thanks.