If one does not yet own own an SA sixgun, it is far too early to think about such a weapon as a carry gun. The limitation of an SA sixgun is that it requires more manipulation than a DA sixgun; more manipulation per shot to shoot it, and far more manipulation at reload time. I give full credit to Clint Smith for the "more manipulation" phrase; I consider "more manipulation" and "less manipulation" to be Clint-isms.
To borrow a term from another well-known instructor, Travis Haley, in reference to fighting with weapons, "Time is life." While he has never, to my knowledge, addressed SA sixguns, he has applied "time is life" to many aspects of the defensive use of other handguns and rifles.
Manipulation. Time.
That first shot is so very important. A highly experienced SA sixgunner can
draw and fire the first accurate shot as fast as anyone can draw and fire an accurate shot with any handgun. After at first shot, however, various sciences are against the SA sixgunner firing follow-up shots as fast as his counterparts
can fire other weapons, because more manipulation is required per shot. In a
real fight, there may be time for those manipulations, or there may not. The
SA sixgunner may be cool enough to perform those manipulations smoothly, or
he may fumble.
Then, of course, there is reload time. I am a believer in carrying multiple handguns, for several reasons, but assuming one is going to carry just one firearm, at reload time, there is no getting around the fact that the SA sixgun requires far more manipulation, during the fight, per cartridge, at reload time. Most fights will be over before a reload is becomes necessary, but as the auto-loading weapon becomes the norm among more of the populace, and the population demographics change, that equation is changing. The fight will be what reality dictates it to be, not what one fantasizes ahead of time that it will be.