As a follow-up to my own question:
Other disks are recognized, raid possible with Disk Utility. WD's utility only complained with a "incompatible disk detected" message or something like it. Didn't bother really testing functionality of WD's utility further.
I'm currently (temporarily) using it with a 120GB SSD and a regular 500GB notebook hard drive until I make up my mind about my back-up strategy and file storage usage.
I'm using these cheap 2.5 inch to 3.5 inch
SATA adapters (in case link goes down, keywords: "2.5. 3.5 converter bracket" & check worldwide shipping) from the
reputable Chinese brand Seatay, since other similar adapters found locally where easily 2 - 3 times as costly (I admit: I'm cheap).
The SATA connectors line up perfectly though the thread of the included screws is different from the screws used to secure the Velociraptors. I followed the cheap route again and used a few pieces of electrical wire shielding (with the actual wires removed) to slip over two of the included screws to mimic the original WD screws. This way there even is some dampening although not strictly necessary.
I had to file the edges of the sheet metal to make the adapters a little less high, otherwise they wouldn't slip in the enclosure easily (one didn't fit at all). Sanded them down to make the edges dull and now they fit perfectly.
Since the warranty was expired on my unit, I also cut the sheet metal in front of the fan hoping to reduce the noise a little when it spins up. I can only hear it briefly during power up, then it starts spinning for a few seconds but it stops quickly and the noise is not loud at all.
Apart from that, the only noise it makes is when Time Machine spins up the 500GB disk (hardly annoying, but still) and the AC adapter making those typical electrical squealing noises (very annoying when it is quiet, probably gonna have to replace that one).
Now, if only those 1TB SSD's weren't so pricey ...
