Not to speak for Karl, because he and I did not discuss this specifically -- but... I think he would say he has already designed what he believes to be the best pocket pistol, in the best caliber for such a pistol, with the R9. I do not believe the R45 is intended to be a "better" R9, but a different gun altogether. I am sure Karl would expect you to carry the R9 in your pocket and/or the R45 on your belt. A larger gun in a larger caliber has plenty of self-defense applicability, don't you think?
However it turns out, it will almost certainly: 1) Be a well thought out design for its intended purpose; 2) Be well manufacturered to exacting tolerances; and 3) Be backed by excellent customer service.
Karl has always had an affinity for 1911 pistols, so it's really no surprise that the R45 design has its roots in a 1911 pattern pistol.