I'm ok with it not being 70's-era C to be honest; I even with the extra stuff, I find the language to be fairly simple to pick up compared to C++.

I haven't had any problem with performance with the Boehm GC personally, though for what I've used C for is not-real-time video processing stuff. I found I typically got better throughput using Boehm than I did when I was manually managing my memory, but for what I was using it for, a small pause wasn't really a problem as long as the throughput wasn't really affected.

One may as well just use C# without classes.

Pedantically speaking that's impossible. But loosely speaking that's the essence of how I write most of my C#.