Horrendous you def need to take off your BE glasses and admit that for once the smaller guys got an advantage.
L410s and do228s are much slower than your q400s so can operate to lower minima BECAUSE THEY ARE SLOWER AND NEED LESS RUNWAY than a q400 at full tilt
So the minima reductions are not the same for all aircraft - it depends on operating type.
You dont need xray glasses just a slower & lower approach