No, you can't go back once you commit the booleans, but that's the same as CAD packages. Once you commit a fillet or boolean, for example, it is tedious to repair no matter what package you're using.

And no, Modo doesn't do 2 rail sweeps, but it does a lot of other things that CAD packages don't.

As I said, this won't be the one true tool because that doesn't, and probably will never, exist. But it's an awesome advancement for subd modelers and it's a direct response to the claims made in your video. :)