Mike, I'm really sorry you had a bad, or several, bad experiences with Colt. There was a time in the '80's when US auto workers were leaving soda cans in doors... manure happens, and I don't know your story.
My first Colt was a 40S&W Double Eagle 4" barrel. Lots and lots of metal. Very little recoil. Shot a thousand rounds through it, learned all about the, it didn't fit my general collecting pattern, and I sold it for the Para single stack I pick up tomorrow (just moving on to another gun; nothing personal about the D.E.).
I next bought the Colt 01091, and there were some machining issues I didn't like. I sent it back before firing it, and they made it more than right. A longtime local firearms instructor claims he never felt a sweeter trigger on a Colt. So I guess you can tell I like Colts. I like the way they are put together. There's only one original.
And the LDA Para Ordnance single stack? I think it was designed by angels. It just floats in my hand.
I have not shot the Glocks; I don't care for the styling, but plenty of LEO's trust their lives to Glocks every day, so I have nothing bad to say about them.
P.S. About going 20K+ rounds? I have several guns with over 2K rounds which still look NIB. It will take a few years before I get up to those numbers, but I'd suspect with regular cleaning of the bore and associated parts, wear should be minimal. If a component is going to break, it should fail within the first few hundred rounds. By 300-1000, I'd expect any gun to be 100%.
An exception is my Inox Tomcat. It was 97% for the first 200-250 or so, and it's been 100% since (700+/-).
I hear of guns being 100% out of the box, but I cannot believe it would be consistantly so for each product issued.
Even a Mercedes has a "break-in" period.