As I work more with my dogs, I'm considering staying pure APBT while selecting breeding pairs for the desired Legionarius traits rather than traditional APBT traits. I've mentioned before that I'd like to mix in other breeds to increase the size of the dogs while maintaining their athleticism, drive, and family orientation. I've been looking for the right dog amongst a variety of other breeds but cannot find an individual that would be likely to contribute desired traits without destroying the traits my dogs already have.
I will continue to keep my eyes open for a potential outcross, but I will not lower my standards just to add some size. I'd rather have the right character in a smaller package than the wrong character in a larger package. This really highlights both the difficulty of good breeding and the importance of character traits over physical traits. Trying to get both right is a significant challenge. This is especially true in today's environment where so many good working breeds have been ruined and no longer carry the character traits of their ancestors.
So we stick with the APBT unless or until we find a larger dog with the right genetics.