There's nothing wrong with cast frames, even Ruger uses them. There's nothing wrong with modern MIM parts. They got a bad rep when they first came out but all those issues have long since been corrected. I bought my Rock Island in 2011. It has been the most reliable 1911 I've ever owned. All I've done is change the mag and grips. It runs anything I feed it including empty cases. It's accurate and reliable, it's just not pretty. So if you want to spend 1000.00 or more for pretty and a name go for it. If you don't think a Rock Island will shoot watch this video of Hickok45 comparing an Ed Brown Special Forces to a Rock island tactical.
https://www.youtube.com/watch?v=3W7sb9Zp-8o
https://www.youtube.com/watch?v=3W7sb9Zp-8o