Sunfish, if you look in Part 61 the requirements for flight reviews and proficiency checks are in there under the heading of limitations on a particular licence, rating or endorsement.
Design feature endorsements (e.g. constant speed, retractable etc) don't have flight reviews mentioned as a limitation on them as, for example, a class or type rating endorsement does, so doing your BFR (or AFR as per the new terminology) in a 172 with none of those things would be fine - it should still cover you for anything in the single engine aeroplane class.
For example, I'm working flying helicopters at the moment, and doing a flight review in an R22 every two years covers me for the single engine helicopter class, including turbine machines (gas turbine engine is a design feature endorsement).
Some things like instrument ratings need proficiency checks (much the same as the old renewal), some need flight reviews (like a low level rating or an aircraft class or type rating), some don't need a review at all (like a design feature endorsement).
The caveat is the general competency requirement, which essentially says you mustn't go and fly anything that you're not full bottle on its systems and operating procedures.
Hope that helps, and vive la revolucion!!!