I think I need a stiffer recoil spring, it is throwing the brass 10+ feet. Should I move up to a 18lb?
Tuning that with the spring is a recipe for problems. The slower you let the slide go back the faster it's gonna slam forward.
Tuning ejection with the spring just means your magazine has to be in better shape to keep up and increases the chance you won't get a slidelock on the last round.
Would you slam the slide home on an empty chamber? No, because it beats up the gun. Changing to a heavier recoil spring when it's not necessary does exactly the same thing over time.
In the extreme a too heavy recoil spring can destroy the extractor by going so fast that new rounds, rather than sliding up under the extractor, get into position so fast that the extractor has to snap over the rim of the cartridge.
The 1911 recoil spring exists to keep the frame from being battered, and to chamber a new round.
Tune the ejection with the ejector, not the spring. They are cheap and easy to replace, so you can grind away on them til you get it just like you want, with no harm done.
But, if your brass is leaving with the exact same trajectory every time that's a very good thing, even 10 feet away.
That said, in a full size 1911 an 18lb spring really won't hurt much, it's when you get to the extremes that you need to be careful. But if you are seeing reliable feeding and slidelock with a 16 pound spring I'd really think hard about changing that.
I run 15 or 16 in my full size 1911's. Some throw the brass to next week some drop them at your feet, depending on the shape of the ejector.
A good write up on extractors and ejectors:
http://www.brazoscustom.com/magart/ejection%20perfection.htm
As for the FLGR's, that's religion not technology