One must know their limits.  But I do believe that humans are adaptable, and can do more than they sometimes think.  For instance, many people say they cannot work a safety under stress.  I believe they usually haven't practiced enough. 

Or they say that a particular gun doesn't "fit them" properly.  My son says that about Glocks, as do many people.  I'm no longer a fan of Glocks, but I adapted to their radically different grip angle (compared to 1911s).  And today you can get them with or without fingergrooves, so I no longer have that excuse.   While ergonomics have become a buzzword among handgunners, consider how much good work shooters did in generations past with guns that today we'd claim have poor ergonomics.  Men like Jelly Bryce, Bill Jordan, and others did very good, very fast work with revolvers that most consider poorly shaped for the human hand compared to modern pistols.  Practice will overcome deficiencies in both the gun and our abilities.

I believe that practice is the bottom line fix for many "deficiencies" we observe in handguns.  By that I mean that if we've defined what we need*, as opposed to what we'd like**, and chosen based on needs, then we simply need to practice to adjust and improve with the handgun we have chosen.

* need-based choices are based on shootabilty in al its ramifications.

** like-based choices are based on comfort and concealability over shootabilty, and light recoil over fight-stopping power.  Also, choices based primarily on other inappropriate features such as guns that are cute, cool, popular, cheap($), and so on--these last are usually choices beginners might make.  Unfortunately, both the gun media and gun retailers push them in this direction.