Floor standing speakers have an advantage over similar quality bookshelves mainly because their larger cabinets allow deeper and louder bass response. With speakers that share drivers, designers, and overall build quality, this should be the only difference. At lower volumes, I see no reason for floor standing speakers.
Although it's true that floor standing speakers take up no more floor space than bookshelf speakers on stands, I think sitting ~6 feet from the speakers is better with small bookshelf speakers, not floor standers.
What was your experience with your B&W 602s? Are they overpowering when 6 feet away, or could they be played quietly and sound good?