How would the DRM free version work with patches? From what I understand, it has been patched a few times and some people are still having problems.

I suspect the DRM-free version has already been patched.
Any future patches would have to be offered as separate downloads, or else a new download of the game offered with the latest patch.

I don't have a contact email for Matt Clark and don't know for sure how patching for the DRM-free download would work. The old contact page at http://www.shadowtorstudios.co.uk/contact.htm
just redirects me to the new website, which looks unfinished.