MaxF: It may help to think of it this way, with A7 you are getting an updated rendering engine. This engine uses a new format (ABT) that improves on the old (BSP) format with much quicker build times and, in many cases, improved performance.

The BSP feature that the Pro owners are getting isn't the same as the one that ABT replaced in A6. The A7 Pro BSP can use arbitrary-shaped geometry, work with ABT, etc. The downside is that this new BSP is a lot trickier to use right than the base ABT system. Thus, Pro only.