I have not used their B&W for a while, so I cannot personally attest to DRM specifically on their monochrome lines, I am currently using the MFC-L9570CDW and updates are not forced. brother has been pretty slow to roll out draconian DRM, though I have heard of it in some colour lines. most brother monochrome lines (from reports I have heard) do not restrict toner replacements - someone correct me if they have personal experience otherwise.
brother support and sales have been pretty good in my experience. give them a call and ask specific questions. in dealing with them I have always gotten honest, straight answers.