19" are note staggered - so at times are the 21". But what caught my attention was your comment that you felt they were quieter. I don't think I've heard this argument before from proponents of the 21". Usually it's looks and occasionally a believe that they provide better traction (but I don't believe anyone has ever shown conclusive data that this is indeed the case). The sales team in Portland and the folks at the service center consistently state that the 21" are louder and less comfortable - and that certainly matches my experience when I had loaners (including one that was in all other aspects an exact clone of my P85D).
21" wheels on the PXXDs are now staggered.
Sorry if it sounded like I was saying they were quieter that wasn't really what I meant. I just made an anecdotal comment that the only 19" wheels I've ridden on didn't seem as quiet. That could have been caused by a lot of things. GG's was built at a different time, so maybe sound deadening has improved, or maybe the wear pattern on the tires was what caused it. He also has different suspension than I do, which could contribute.
Low profile tires are definitely louder and harsher. If I put 19s on mine it would probably be smoother, but by how much? Maybe a lot of people that say they are super harsh drove them before a change that was made and maybe the 21s aren't as bad anymore. When sorka rode with me he commented that 21s on his would be much harsher.
Also keep in mind that they stopped running Michelins a while back and suspension changed since then (according to various data points in threads) so going back to Michelins and combined with a different suspension may make a difference.
I guess what I'm saying is, if 19s used to put out Xdb of noise, and 21s put out (X+5)db, but 19s now put out (X-5)db and 21s now put out (X-1)db, then they are quieter than 19s used to be. Still louder than 19s, but better than the 19s used to be and that might make them more tolerable for more people.