Is the Simba Hybrid noisy? I have heard the microsprings can creak.

Not in our testing. The Aerocoil microsprings are small conical springs set in foam, not interlinked coils, so there is nothing to rub or creak the way an old open-coil mattress does. Any creak people report usually turns out to be the bed frame rather than the mattress, especially on slatted frames with loose slats or a centre rail that has worked loose. If yours creaks, lift the mattress off and press on the slats to find it.