At $600, it’s a very affordable competitor to other Thunderbolt storage adapters, providing 4 SATA III 2.5″ slots and a daisy-chainable Thunderbolt 2 interface.
This should enable you to run 4 SSDs in stripe mode to fully saturate 20Gbit/s (2.5GByte/s!) on Thunderbolt. Something like 4TBs of storage including the dock would cost you around $2000. Can’t wait to get my hands on one.
It also gives you the flexibility to ingest a HyperDeck recording from one slot to a software raid on the remaining 3 slots.
Larry Jordan correctly points this out: Thunderbolt has long outrun the transfer speeds of spinning hard drives. Spinning 3.5″ disks deliver around 120MB/s. If you stripe four of them, this would give you about 500MB/s of transfer speed. If you go for a larger 8 disk unit, this would max out at about 920MB/s.
So now the tradeoff is storage size vs speed vs price vs weight vs dimensions. Choose what fits your needs best. Granted, the MultiDock really belongs in a rack and will look a little odd sitting next to your shiny new Mac Pro on the desk.
As the new MultiDock also supports daisy chaining up to 6 MultiDocks, you can get a setup with up to 24TBs of storage at 20Gbit/s for “just” $12k (cables not included).
Another first notable first in (my) zoo of Blackmagic devices: the power supply is built in and doesn’t take up precious space on the bottom of the rack and on the power strip.