9mm "Why would you want to chop your gun up?"
Watch the video, longer sight radius & more weight for less recoil.
Honestly, I'm surprised more companies don't offer pistols like this in a factory configuration. Aside from the Springfield XD and 1911 which can be had with the smaller lower and longer upper half, I don't think anyone else is really doing this. The benefits of the smaller frame for carry and longer sight radius/barrel for velocity/accuracy are exceptional, so it seems it would be something more popular. But perhaps there's not enough of a market to justify the production costs?