At this point it really does ...

At this point it really does not matter as all of the vendors have good products and as long as you use the vendor recommendations for flux rate and pressure you will probably have good results with the system.

In an Out/In system, they will tell you that you get more effective membrane area for the same number of fibers. But they don't tell you that you don't get completely consistent flow distribution so some fibers are left dealing with more concentrated solution than others.

In an In/Out system, they will tell you about the controlled feed flow, but they will downplay the energy requirements needed to get that controlled flow.

It all depends on the actual characteristics of your water. Request quotes from multiple vendors and see what shakes out.