Good point on the SSD's.
Also, those .5TB 10K drives are geared more towards a system that has a
mix of faster drives and these slower drives with balancing enabled.
Wouldn't really help you because your spool data would probably still end
up on these slower drives and your backup would still be a dog.
Does your PRTDSKINF show more data on production tied up in spool files?
Granted you have more spool files on production. However, this may not
equal more spool data. (Think size of spool files also.)