Very interesting topic indeed.
From the bit of reading I have done, although it's a "legit" key, they all differ widely when it comes to the actual terms of use of the license, meaning the R100 keys are often more rather a grey product (ie meant for a different market), rather than an illegal product.
In the grand scheme of things, probably doesn't make much of a difference as a private home user - since I guess it would be really hard to enforce, but on black and white it's potentially breach of the licenses T&C's. and the distributors could probably get sued.