advantage: You get that bass impact that is non existent with small speakers provided that your AVR or Processor can set the surrounds to Large. IMHO it gives a fuller representation on surround effects. Contrary to popular belief, there is substantial bass information in surround effects. Having floorstanders as surrounds let you take advantage of those missing low end information often lost in small speakers thereby making the surround experience even more realistic.
disadvantage: in my case I had to find a way to at least have the tweeters of the speakers to be above ear level. 6 inches above ear level works for me.
