I'm just relaying what experiences I've seen. 1911s are known to have tight tolerances as needed on a metal frame gun. Metal on metal movement is different then steel on polymer, and in my experience 1911 slides are made out of thicker steel than poly guns. Yes, there are spring replacements, and maybe your 1911 was better designed to compensate for any 9mm issues. All I can do is relay what I know, and show you how to spell steel.
Ha! I edited my post before you posted because I realized how stupid that looked.
You posted your experiences and then made a comment regarding physics as if it is a foregone conclusion that the 9mm WILL be more unreliable. I then posted my own experiences asking you what the difference was. Yours were of knowing of some 9mm 1911's while mine were of actually owning and operating them. Granted, still a minuscule sample size. No need to take it personally and resort to finding spelling mistakes.
I'm no expert, but I'd like to know if you have more reasoning behind your distrust of 9mm 1911's. The 1911 was based on 45 ball ammo and didn't have a ramped barrel. Most 1911's you get now come with a ramped barrel to help it with HP ammo and in turn, pointier rounds like the 9mm.
If you're talking a difference of steel on polymer vs steel on steel, then how about other metal/alloy framed 5" 9mms? Sig makes their x5 series in 9mm, and CZ makes their tactical sports in 5.4". I'll point out and admit these are competition models though. The other thing is that even the polymer guns will have metal rails that the slides will ride on. The only thing I can think of that would require additional force would be to overcome the additional friction caused by the larger contact point of a tightly fitted barrel bushing.