I can speak from personal experience BFL has a completely terrible customer service (basically none) and they deliver MUCH later than promised. (Several months), which means that by the time you eventually get your product, it will be hardly making enough bitcoins to cover the initial investment.

In other words, don't buy anything from BFL.

I ordered a BFL 25GH/s in April and they said it would take about 2 months to deliver, they delivered it about a week ago. It now makes 0,02bc a day, so it will take roughly 2 months at this difficulty to pay for itself, however the difficulty will likely increase so it may not ever pay itself back and will be even less likely to make profit.

Also by the time they deliver the $/gh ratio and the kW/gh ratio are both pretty terrible.