as far as the queen ex ,, some swear at it some by it ..
it keeps the queen out of the honey super , some say it keeps the honey out ,
by that I mean they say its hard to get the bees to go thought it ,,
on two hive3s of mine this year I didn't put in a excluder ,, for reasons of my own I didn't get in the hives like I should of , just added a med , I now have two deeps one med ,, just as full of brood as it can get ..
I think you mean a inner cover ,,,
will it get through the summer with out ,,, yes ,,, I was short a inner cover
( again short on time ) , I put a 8 inch long 1 by , on the frames then put the outer cover on ,, did it make it through the summer , yes ,, do you want to try a winter without one ,,, NO