If you are going to use as a carry piece I would not get a Monolith because you may have difficulty in finding holsters for the extended dust cover 1911. Also I had a G&A magazine that had a shoot off from a ransom rest with the Monolith against the Premier II and the PII had much better accuracy in that particular test. Personally I wouldn't get the extended dust cover unless I needed a mounting rail. Also, the traditional look is appealing to more people which could make resale(only in emergencies) easier too. Then again we all get what we like. So if you like it, want it, and can scrape up the money, then go for it.
I have a Baer 10mm heavyweight monolith and really love it. I specifically went with the monolith to try and increase the weight in the slide and frame because I shoot "full house" 10mm reloads and I wanted to buffer the force. I found that with the 1.5" 50 yard guarantee (it will do it to!!!) it was pretty tight for the first 1500 rnds or so, but since then not 1 failure to feed in the last 2000 rnds or so.
I had to weight about 16 weeks for mine, but it was a custom 10mm, and not a standard 45 or something.
You should handle one if you can. The additional weight at the muzzle end gives it a solid feel and seems to help speed up re-acquiring a sight picture for rapid second shots. I sent mine to Blade Tech for a custom holster, and they kept a mold, so they can make a holster for Monoliths, and so can Lou Alessi. I like the look of the extended dust cover.