4 layers of DV playback needs a 4 x Raptor RAID though
please - you need to test with YOUR content - or something like your content - as photojpeg has different performance for each file and different compression settings.
its quite variable. it is very difficult to give general performance guidlines outside dv files - as every file is different.

the performance of dv files is constant because they have a fixed bit rate.

start with something minimal - say a single raptor - no need to do any kindof raid to start with- and see what happens.
tell me what you see. please.

typically - you will not see any performance difference at standard definition - with your files at 768x576 between a single disc -and a raid system.
raid systems are only important when the data rate is the limiting factor - in uncompressed movies.