In my experience, I’ll take Prores any day. DPX is nice, but so far I’ve experienced some frame drops (though at 10-bit 2K), but I’m usually in the green and have good performance.
One frame of DPX takes far more space than one frame of Prores 422HQ or 4444, thus you’ll need faster communication between file -> Resolve. A RAID is the solution, how fast it is depends on what kind and how many disks you make it up of I guess.
I have 4TB RAID0 on eSATA. RED RAW, DPX, Prores 4444.. no problem.. But I experience DPX as the toughest one to chew.