I'm always more comfortable with service calibers.
Anyone in a defensive situation would prefer to score hits on an attacker with a service caliber.
Anyone who can carry a pistol with which one can reliably do that would be well served to carry it.
But the rapidity of fire that may be needed in a defensive situation makes the use of a small, light pistol in a service caliber an iffy proposition.
So, it depends on the gun.
Forget shooting groups at the range. Go and participate in, and/or observe, a real defensive training course. If they offer an El Presidente drill, or a variation thereon, the purpose of which is simply to measure and increase shooting proficiency, compare the performance of shooters using full-size M&P pistols , Ruger American Pistols, and Sig duty pistols with those using smaller and lighter pistols in the same calibers.
You will surely note that the performance of the shooters, becomes progressively worse as the sizes and weights of the pistols come down. It is not a matter of whether the shooters think they "can handle" the increased recoil, it is about whether they
score hits rapidly enough with a gun that recoils more severely.
In such a drill,
and in a real use of force situation, most people will do better with a full-size duty pistol--as Buckeye puts it, "a real pistol in a real caliber".
but most of us prefer to not carry duty pistols concealed all day. We compromise by carrying smaller pistols.
Large numbers of shooters who have not participated in realistic training and have not thought in terms of a realistic balance of speed and accuracy have been selecting smaller and smaller pistols, having convinced themselves that that "service caliber" chambering will provide the effectiveness that they need.
The Springfield XDS 9 is a case in point. The original with the 3.3 inch barrel was popular. When they introduced a version with a 4 inch barrel, Trainers and reviewers raved about how much more shootable it was. But due to lackluster sales, it was discontinued.
I carried the 4 inch version. I would not carry the smaller one.
I have a Ruger American Compact pistol Good gun--but I would not want one of their little 9s.
Same with Messrs. Smith y Wesson. I'm okay with the EZ 9, but not with their small 9s.
Yes, I too am more comfortable with service calibers--in the right guns.
I recently decided to acquire a much smaller and lighter pistol, primarily for backup.
I chose the LCP Max.