I've done quite a lot with the ML family, just not OCaml specifically. Type inference helps, but being able to use an Sexp-style representation a-la lisp is a huge, huge benefit in compilation. You cannot do this in any of the ML family.

Pattern matching is a great feature, and it's available in all of the languages I mentioned. It's a built-in in Boo, there are many libraries for it in Scheme, and I have my own Sexp pattern matching libraries for Python and Ruby. It may have come from the ML world, but it's by no means exclusive to it.

As for proving correctness, depending on the language to provide this is simply not realistic in compilers. You've got a much better shot at correctness by making your compiler easier to work on, IMO.