I don't think the slatted racks make the mice any better or worse, they do tend to build their nests underneath, but if they arent' there they just tend to build them on the bottom bars of the combs after they chew out an area to do it. The slatted racks will not keep the mice out or in any way mitigate the damage, nor will they make it any worse. The mice will still get in. They will still eat the bees and the honey and the brood. Still chew up your frames and smell up your hive.