David, I get that having a purposefully built pistol, from the ground up, for the caliber you are expecting can be considered a desirable scenario. But to your example, there are chassis made for several different engines. The designers have a range of things to consider when designing, and different engines with HP and torque may be one of them.
In the end, it boils down to design input requirements. What must that pistol frame support? What loads must it accommodate? What mean time between failures must be achieved, and what total round count must it endure? Truth is, there's engineers who get paid full time to think of these things in design. There's then a whole bunch of engineers and technicians that do hands-on design verification to test. There are probably over a thousand design requirements that get considered when designed, and then these are tested.
The best companies (especially the ones going for lucrative military contracts) will try to do as much actual testing as possible to uncover design issues. Decent companies will more likely take limited data and extrapolate to the extremes of their requirements. And craptastic companies will likely just perform a paperwork analysis only that says "we checked our facts against our facts and found our facts were facts".
Bottom line, you have every right to your preference. My recommendation is that you go beyond preference, determine what your design and usability requirements are, and ensure the firearms considered actually meet those. 'Converted' designs (from 9mm to 40) are not necessarily bad, and may meet all requirements imposed on them.
D
