ANOTHER 1911 guy here, and I recently committed to buy a Gen 4 G19. A long, arduous and horribly over-thought process, brought me to that conclusion. I like other guns better, but they don't have just the right combination of characteristics as the G19 does for this specific intended purpose. (the feel of the Glock grip angle was always the big hangup for me. The Gen 4 seems to solve that issue)
I'm pretty handy, and so tools, their function and usage is pretty 'common sense' to me. And while I see the point and perspective of the folks that say "stock it what makes it Glock", there are virtually countless reasons why any aftermarket industry exists. (trucks, diesels, cars, motorcycles, guns, marine, etc)
When a manufacturer makes a product (any product) they do so to appeal to the widest market, the most possible people (or in some cases, meet a gov't or industry regulation) I installed different tires and shocks on my truck, because I like how they work better than the ones the factory installs. When I paint my house, I use a brand/color/sheen that I want, and what works for ME. Making mods to a gun is no different, (from my perspective).
When I built my Jeep, I can only guess I had over $50K into parts and materials over the 15+ years of modding, and building, using, breaking, modding, building, etc.... if I had to do it over again, I could do it for a lot less, and would know exactly what I need to do, without all the trial and error. But.. that trial and error taught me a TON. Again, guns are no different.
So, with my life experience, I suggest that yeah, you do shoot it first, but try others that have done mods to their guns, see what mods they have done that you like. Don't be afraid to try some of the mods yourself. (Youtube has some fabulous how-to videos on just about every subject under the sun) When you do the mods on any mechanical device yourself, you're intimately more familiar with that product/tool/machine. Go slow, be patient, take lots of notes, measure 4 times, for every time you want to cut or grind something. Again, be patient.
I've had some of the most rewarding experiences when I did the work and my mods did exactly what I wanted to accomplish.
I do realize there will be others who differ from my opinions, but those are just my opinions, formed by my experiences.
PE