I have a Gen 4 19 and I have fired over 500 rounds through it. It is comfy and sure in my hand. I see people remove the grooves all the time and i did have a gen 5 for a bit. The gen 5 was nice but I did not like the cutout after a while. I do not remember thinking wow, the grip is so much better without grooves.
Now I look at my grip and over analyze it and think if I should invest money into finger groove removal. I wonder as far as the gen 4 is concerned if I am really missing something? I know this is such a personal taste and everyone will be different, and also that I would be able to work with the modded or factory setup.
But has anyone been on the fence about this whenever the factory grip is really just fine to them? Honestly if the internet didn't exist I would never know about the possibility of removing the grooves, lol