I take it an RFDS King Air pilot who does his multi IR every year, but owns a Bonanza, will need to do a renewal in the Bo at least once every two years .......because instrument flying a B200 is just not enough
It seems that's about the size of it ... not the most sensible sounding concept in the world, really!
What about CASA nominate your 'most complex' type and you have to do the renewal on that at least every 2 years, and every other year on that or any other IFR type you're rated on?
Not that it worries me at the moment, the most complex instrument in my current selection of flying machines is probably the clock!