I've been using both a Weathershield and a Noah together, absolutely no moisture entrapment issues. The rain rolls off the Weathershield, the Noah blocks any mositure that seeps in and provides extra paint protection and weight necessary to keep the cover stable in the elements. You can wash the Weathershield in a home washing washing too
As for stray cats or other creatures, a few years back something ripped holes in my gf's Noah and must have crawled on my Noah an slid off

with very minimal damage. We now use both covers, rain marks are virtually non existant except very minor after very heavy rain. The covers are a blessing during snowy weather too.
Absolute best investments I've made for my car.