I thought this was exclusive from Subscribers only? I checked out the link and it doesn't really go into much detail about the differences between the non-subscriber SB users and the subscribers.
I thought the primary reason of subscribing (besides supporting the communtiy and Stardock) was that you then were able to use SB exclusively.
If people have access to SB and don't have to pay the subscription, they don't have much incentive to ponie up the 19.95 (other than the 100mb limit).