M/S... you're taking a figure 8 mic, splitting the signal [as there is only one output], taking that signal and flipping one side 180˚ out of polarity with the other side so -- when of equal level and put in mono, the two sides of [the identical signal] will cancel... the forward facing cardioid microphone being unaffected by the polarity reversal.
Even if RØDE built 100% "perfectly matched" microphones -- due to placement [spacing between the two capsules] they would never cancel 100%... they might get "close enough for jazz", but they will never 100% cancel.
This is not to say you shouldn't try the technique [who knows, it could be awesome for your application(s)], but it will NEVER be true "M/S".
Peace