I am not sure that the Replacement parts would make a gun less reliable. Changing out the barrle to a WOLF so you cna shoot Lead, adding a lighter striker reduces your lock time as the lighter striker under the same spring will make it faster. Using a lighter metal that is stronger than steel like Tititanium would work. Changing the trigger from a standard to a shorter reach should not be a problem. Well I say that it should not be a problem, unless the part was improperly installed, the gun is improperly reassembled or is a faulty design that causes problems.
The choice between a Small Glock and a Small revolver is a personal choice. Depending on many factors.
Your size, can you hold each of them confortably, and shoot them with one hand and not have to adjust it with the other., can you get two hands around the gun?
Now the only thing that reliability has to do with the gun if both are working well and you can handle the recoil and manage it.
(manageing the recoil on the auto will change the function of the gun. Let's say the slide need s to travel 2" and you move 1" the slide will only eject the old case and will not load a new one.)
The reliability of a good gun is going to be more with your ammo. In the Auto if you have a dud round you need to tap and rack, with a revolver you simply pull the trigger agian.