In terms of performance shooting, there is a sliding scale between guns that are easy to shoot, and guns that are easy to carry. Generally speaking, it is a trade off. There is typically a balance point, where a gun can be carried concealed relatively easily, but still shot to a decently high level. The Glock 19 is one of the guns that falls on this balance point. The Glock 19, and its similarly sized peers, is a Goldilocks gun. As small as you can get without giving considerable performance.
So when it comes to back up gun sized blasters, that are minuscule compared to even a Glock 19, what is being given up for the convenience of a smaller gun? I tested this with a P380, and a Glock 19 sized carry gun. I only tested it with regard to accuracy so far, but more will be coming.
This is a 5 round group with my prefered 9mm carry ammunition. It is a decent group for being shot freestyle from 25 yards. About as good as I am capable of.

I followed that with a five round group from my P380. I was using PPU First Defense JHP in the P380.

So the question is, does it really matter? If those two targets are scored based on point value, the P380 pulls in 44 points, the P250 pulls in 47 points out of a possible 50. Even though the point values seem close, if you look at those two groups, the size disparity is significant.
Personally, accuracy matters to me because of what I expect from a handgun. In order for me to carry a gun, I need C-zone hits from 50 yards at a minimum. We carry handguns because they are easy to carry, but we have to be able to solve a multitude of problems with them. That means being able to shoot them at distance too.
Even though at 25 yards the P380 doesn’t look bad, at 50 yards it gets a little dicey. Dicey enough that I didn’t even bother taking a picture. I don’t thing it is because the gun isn’t capable of it, but because what the gun is makes it difficult to accomplish. Specifically, small sights, and a very short sight radius. The short sight radius means that even very small deviations in sight alignment that normally wouldn’t be a big deal on target, are a big deal. It is a problem inherent to the size of the gun. Maybe with more practice though, I can reign even the P380 in.