everyone has their own definition of quiet, but id tend to listen to EVH on this. he knows what he's talkin about.
also from my own experiences with the few shuttles ive had. they are quiet. i have noticed that the newer the shuttle, the quieter they get.
reviews only say it will be like a jet engine because they see the words 60mm fan etc and instantly assume, small fan, must be spinning really fast otherwise they dont push any air, so it will be noisey....WRONG! it doesnt have to spin full pelt to move air, to be fair it doesnt really have to push much air, just enough to keep the airflow circulating.
right now with my shuttle SN85G4V3, all i can hear is my raptor. this is a new one since tee last one died and i havnt done any modding except an arctic cooler, so its all stock fans thus far. it currently hasnt got a case on and its less than a meter away from me and its barely audiable.
if you want absolutly, totally silent then your lookin at the wrong systems. you should be looking at mini-itx boards and mods on making them totally passivly cooled, cos thats the only way your really gonna get anything quieter