I'm a little late to this thread, but what the heck, I'll add my two cents to the discussion.
I currently have 13 1911's. Two are WWI US Property marked Colts and one is a WWII USP marked Colt. My oldest 1911 was made by Springfield Armory in 1914 and the newest was made by Colt in 2013 as part of the Marine Corps MARSOC contract. Three were made in foreign countries, Argentina, China and the Philippines. Over the years I have probably owned a few dozen others, but sadly they have been moved on to other people.
The reason why I listed my modest little collection is not to brag, but to show that I have a fair amount of experience with a decent variety of different 1911's, made by a number of different manufactures in four different countries to base my observations on.
First, they all shoot very much the same. Different sights and better triggers will make the main difference in how accurate they are up to a point. After that, the quality of the components and how they are fit together make up the rest of the equation. The 1911 has a very easy trigger to alter the weight of pull and there must be a few dozen different people making sights, so changing the trigger and sights is a faily easy thing to do.
As for the difference between the pre series 80 guns without the hammer block safety and the series 80 guns, it is a matter of a few minutes and a couple of dollars in parts to remove it and presto! you now have a pistol with the pre series 80 trigger. I have done a couple of them and IMO, you would have to be nearly hopelessly incompetent to be unable to do it yourself. As a side note, while the best trigger of all my 1911's is my 1974 vintage Gold Cup, a very close second is my series 80 Officers Model that still has all the hammer block components installed and functioning, so you certainly can have the hammer block system and still have a very nice crisp trigger.
I find the whole internal vs external extractor debate to be a silly thing to argue about. A wide variety of guns use external extractors with no problems including guns like my Browning Hipower and my Stars. So far I have had zero extraction issues with them that wasn't traced back to the ammo I used, just like I have zero issues with my guns with internal extractors except for occasional ammo malfunctions.
As with all the "which gun should I get" threads, you will always get lots of posts that simply state what the particular poster likes/dislikes based on their experience or lack thereof and my opinion is no different.
I am a Colt fanboy and I make no apologies for it. At a price point under a grand, you would be hard pressed to do any better, but I also think the Springfield offerings are a good alternative. If you want to get your feet wet in the 1911 game without spending a bunch of $, get a Rock Island Rock series which comes with the upgraded sights hammer and trigger and shoot the heck out of it. You will be surprised at just how good they are, I know because I have owned a couple and still have my GI model.