I would say there is an issue with your drive.
I have my SD setup exactly as described in post before yours and never had any errors.
I think different devices react differently depending on what filesystem is used.
I do however set block size to 1024 for boot (2gb) and my larger drives (28gb each) as 4096.
As a rule I use the following DOS Identifier for PFS which is: 50465303
Why not Direct Scsi PFS3?