[TripleD]

I have Holosun 507C optics on 3 of my pistols and a couple of their 510Cs on AR pistols and I really like them. As a previous commenter said, using one on a pistol does take a while to get used to it and finding the dot, but just as with finding the front site in a defensive situation, practice, practice, practice. The repetition will build the same muscle memory with finding the dot. I run suppressor height sights so my dot is basically sitting right on top of the front site.
As for why Holosun? I believe they are the best "bang for the buck", they are reliable, great battery life, solar equipped, and "shake awake" and they have a 2MOA dot with choice of a circle as well.

 

[TripleD]

Also, The first one I got I mounted it on my pistol with an adapter plate as it did not have a cut slide. I used a little blue loctite on the screws and have put 700+ rounds, some of them fairly hot reloads, through it with zero issues.

 

[TripleD]

I really don't have a red dot ready pistol, so it would cost a lot to buy and install one. I have found that fiber optic sights are really nice on range guns.

If you ever wanted to try one without having to by a new slide or gun, try one of the adapter plates from egwguns.com. I have one on a Glock 21 and it works fantastic. Other than raising the height over bore a tiny amount and adding less then an oz it functions like my newer guns with the cut slide.