It's all personal preference. Bluing, parkerizing, duracoat, etc, will show holster wear more than a stainless, which won't show much, if any. I can't speak on a weight difference, but I would have to guess it's negligable if there is any at all. I personally wouldn't want to carry a stainless gun with no coating, because if you happen to accidentally expose it, shiny stainless is a bit more obvious than matte black.
Can't argue there, I've got one stainless with black hardware and I'm picking up a TRP operator by the time I get back from Afghanistan... so there's my black gun
When I bought my SA Loaded, I faced the same decision. I went with the parkerized, it's already showing some holster marks. I'm wishing now I had gone with the stainless.
Since my sweat corrodes even Kryptonite, I would opt for stainless. I have 2 1911's that are hardchromed, and it looks like stainless and I have had no corrosion problems. I have had these pistols several years. They sport no wear marks either, and I carry one or the other most all of the time.
Blue is pretty and "traditional" but a good deal more decorative than protective. I carried blued weapons for years before the introduction of stainless. They required daily inspection and vigilant care to maintain them properly, which can become all-too-easy to put-off in favor of other concerns in everyday life.
IMO, there are two primary factors to be considered: Resistance to corrosion and resistance to wear and abrasion. Stainless offers much better corrosion resistance, but not much of anything better than good 'carbon' steels when it comes to wear resistance.
Best of both worlds, IMO, lies in hard chrome or one of the many other proprietary metallic composite finishes applied over a stainless base. I've had very good service from Armoloy, Tanfoglio's "Wonderfinish", Star's "Starvel" and Robar's "NP3".
There are two more finish options not mentioned. Park'd, which feels cheap, but does a better job of protection and wear resistance than blued, and my preferred finish; stainless with a layer of duracoat/paint. The stainless is less than ideal for carry (not for wear, but appearance). And although I do not usually carry a 1911, and it doesn't see the light of day, I still prefer not to have to worry about it.
Are you really considering carrying a 1911? If you have the right body build, you could pull it off but I can say that I found it very tiring. If you're not carrying than get what you want. Stainless definitely looks BA but my favorite is definitely the SA TRP with the Black Armory Kote