Honestly, a modern Intel processor with quick sync will do a far better job of transcoding than that p2000.

I have 1gb/s synchronous fiber through my local small town. $80 on my city utilities bill. Oh, and no caps. Muni fiber ftw

I use Unraid as my server OS. It has a mechanism for caching file writes to the slower array disks.

Massive SSDs? Nah, just a couple of 1TB drives as cache. The rest of my 120TB is spinning disks :)