Brumbal :
For answers directly from WD check this link:
http://www.wdc.com/wdproducts/library/Flyer/ENG/2278-771046.pdf
I agree that you should check with WD to see what they say, instead of assuming someone's anecdotal evidence for their setup will work for you. I will add that this flyer is from 2012, and two years later WD's official word has changed just slightly; q.v.:
http://wdc.custhelp.com/app/answers/detail/a_id/1397/~/difference-between-desktop-edition-%28wd-blue%2C-wd-green-and-wd-black%29-and-raid
and also:
http://wdc.custhelp.com/app/answers/detail/a_id/996/session/L2F2LzEvdGltZS8xNDI2NTE5NjE3L3NpZC9XZG1oVHNobQ%3D%3D
To summarize - Blue, Green, Black, Red are consumer drives, and are not designed for RAID other than RAID 0 or RAID 1. (Green should not be used in RAID at all, and Blue is iffy).
BLUE - normal drives for desktops at a (normally) cheaper price (and quality)
GREEN - lower power consumption if used properly, slower, and not for always-spinning activity; most 'eco-friendly' (if used correctly)
BLACK - higher cost, higher speed, longer warranty. Supposedly failed Enterprise tests, but still work fine
RED - for SOHO NAS (note - they don't say full RAID, just 0 & 1)
VelociRaptor - Enterprise Workstations - supposedly similar to BLACK, but RAID 0, 1, 5
Enterprise - passed all endurance tests - fast, expensive, and good for almost any RAID; Some have a shorter warranty since these are intended to be used harder
Will drives work outside their intended range? Sometimes, or more likely for awhile. People have said they've run GREEN in RAID for years. But are they talking RAID that is reading/writing continuously, or in more normal household applications with RAID 0 or 1? Did they luck out so TLER* doesn't kick in. Some motherboards wouldn't even know what TLER is, nor would they care that a drive was failing, hence would give no report of problems unless queried. So somebody saying they've succeeded in mis-using their drives is like any other overclocking - useful, fun, and continued success not guaranteed. I hope you also back up. I have no problem with overclocking or hacking a device to do other than it was designed for, but I also accept that there are risks. I choose to do things like backup to minimize (but can't do away with) the risk. One way to minimize those risks is to study the facts to know what it is you might (or might not) want to hack, and to find out other people's attempts at the same & learn from their anecdotes where to be more (or less) careful than 'the book' says.
* TLER: time-limited error recovery in enterprise drives, as vs the BLUE, GREEN, and some BLACK which use a deep recovery cycle to catch errors, then fix them by moving the data sectors, etc. This takes time - often enough that a true RAID appliance would reject the drive. The Enterprise drives TLER are required to make a decision about an error within 7 seconds so a true RAID box won't toss the drive out of the RAID array. Does a failed enterprise RAID drive relabeled as a BLACK drive have TLER? No, it would have the consumer BLACK software installed in it's firmware, though I did once receive a drive clearly labeled on the drive itself as BLACK that had TLER. I never knew if it had the wrong sticker put on it (ie, I received an Enterprise drive at BLACK pricing), or if it had failed tests, and did not get the correct (BLACK) firmware, or if they ran out of BLACKs and decided to ship an enterprise re-stickered. (I put those in order of likelihood. What's the difference between the first choice and the last choice? Intent: the first would've been accidental, the third would've been intentional. Why do I consider the first more likely? I was overdriving it in a corporate environment and it's still showing no problems after 7 years.)