> 3. Pure s/w RAID10 if I can convince the PERC to let the OS see the disks
Look for JBOD mode.
PERC 6 does not have JBOD mode exposed. Dell disables the feature from the LSI firmware in their customization.
However, I have been told that you can convince them to tell you the 'secret handshake' or whatever that allows JBOD to be enabled. The more adventurous flash the card with the LSI firmware, though I'm sure that voids all sorts of support from DELL.