The specs are 1000mA for the + and -12 and 500mA for the +5. I believe the 3000 refers to the actual transformer.
I own a couple of these and quite a few Tiptop ears/rails combos. I never thought I'd say this but the Bs feel a lot better build quality than the TTs. The latter feel like a rush job, with sharp and pointy edges, and generally flimsy, while the Bs look and feel properly finished and robust.
Problem is... I run for my life when I see sliding nuts... I only got those two because they were for a dedicated System 100M where all the modules would just stay where they were from day one.