as a general rule michelin set them up (design) so they were generally very evenly so they last a long time but replace at the same time but sometimes ive read with trials or road versions of those the fronts can wear quicker than the rear.
if your killing rears really faster that fronts its either rider habit or bike set up.
contis aint a bad tyre, its more of what you want out/need them to do differently to what your old tyre couldn't...where the michs too soft carcass so its vague and bouncing even with high pressures, drops into a corner suddenly, wears weirdly? if so then pir/metz/avon/contis reasonably if same typr/models,selected in that order.