Padwan - There is nothing like a 1911 as you have discovered.
I have a Kimber Custom II. It was my regular carry gun, range gun, EVERYTHING gun for well over 4 years. That thing went everywhere with me and it shot with anything that I fed it.
Now, I have heard
several complaints of Kimber's Quality slipping lately, but I have yet to see a true to God example with my own eyes.
With $1000 to spend, there are a lot of weapons to consider, both new and slightly used.
The first thing I would recommend is to hit a few gun shops and see if there are any "higher" end models that are on consignment or for flat outright sale used.
Around here, in the Tacoma area, I found a ton of used 1911's that were $900 to $1200 when I was looking for a good "cheap" 1911 to put through some tests and ultimately set on fire and shoot.
Anything that is below $450 or so is selling like hotcakes, regardless of maker. However, higher end models from quality makers ( like Sig & H&K ), and 1911's, are sitting for months. You might be able to walk in and get yourself a deal on a loaded Springer or Kimber or a semi custom.
If you want a new one, there are a lot of options and I would recommend you shop, test fire, handle and play with a lot of them BEFORE you put your hard earned money down.
I still like the features of the Taurus, but most of the Interwebz hates them. Stalkingbear has one and it shot great for him.
Now, on to the question of a steel frame and an aluminum slide, I will give you this lesson that was gleaned from my own experience.
I bought a Beretta 92F back when Lethal Weapon 1 was just known as Lethal Weapon.
The 92F, at the time, had a steel slide and an aluminum frame. It also had a monster grip and a slide mounted safety, which I now hate since being educated by the world of Browning.
After 5,000-6,00 or so rounds I was able to actually see a difference in the wear on the guide rails on the frame of the 92. There was a physical wear and it was not even, the Right side had more wear to it.
I still presume that was because I was the only one who shot it & the Beretta has a right hand twist barrel.
Now, that was back a million years ago when I was but a wee-pup in the yard.
Honestly though, I don't trust the wear rate on dissimilar metals. Aluminum is going to wear faster than steel. That is a fact. And even if you add grease or lube or the best liquid ball bearings available, there is still going to be metal on metal wear.
Padwan, I would really try to steer you away from a pistol with one form of construction on the frame and a different one on the slide.