Can I throw something out there, that may create a discussion. Have you tried a shaving oil or Prorasso Pre-shave cream? When I first started, I skipped this pre-shave prep and I got razor burn, but not as bad with my Mach 3. Since then, I am mostly burn free.
The other thing might be an allergy. I have an allergy to lanolin, which is present in MWF and a few others.