No SCSI HD's are quiet IMO. If the motor noise is quiet then you will still get stung with the head seeking noise :/
My Maxtor Atlas III's are fairly quiet in the motor department, but once they get seeking you aint going to be sleeping if its in the same room

Also theres a resonance about them that niggles me.
If you want the reliability of SCSI you could do what ive done and IDE raid 1 all your rigs with quiet (fluid bearing) HD's and just replace them every 18 months or so.
I try not to keep IDE HD's for too long as ive had such bad luck
