Picking up some hotspares in advance would be a good idea. Also taking these notes into account.
Recommended storage scheme for home server? (LVM/JBOD/RAID 5...)
See footnote  in above link to see what happens with cheap storage when you need it the most.
This is all a moot point however until you profile how your the target application actually uses storage. You might find that parallelism is possible, so one block can be used for reading results, and one for writing them. This could be further abstracted behind a RAID0 (until the HBA reports QUEUE_FULL) with the results backed up via rsync.
It really depends, saying "I'm doing image analysis" without defining the workload or level of service just isn't enough; even if you did, that level of performance analysis is real work, I know it's something "I" wouldn't do in my spare time. My intentions are to get you thinking about your application to create your own solutions. Spindles are always the slowest part of your system, plan accordingly.
One idea if you wish to do the multi-array approach would be creating two RAID 1's, on separate controllers, and adding those MD devices to a LVM VG for management. Sure a RAID 10 is fast, but it's still one storage queue, now you have two, and with separate controllers there's no HBA queue sharing either.
Remember, SW RAID is no different than HW RAID, understand how it works or when it fails you might end up being more at risk as opposed to say spending your energies creating a regular backup strategy (rsync.net) instead. I've lost count of the number of users who've lost everything because they didn't read the manual and actually test the failure modes.