Yea, I'm familiar with the 'point of diminishing returns' been there before. Trying to ward off my worst nightmare which is the stories I've read here about perlite little by little finding any opening and sifting down. One post talked about it pretty much emptying his flue. I realize that whoever it was probably didn't take the precautions I am but I just don't want to have to do this again. It would really tick me off if for some reason I did and and I knew it was because I didn't do a couple hours more work on it. I'll not know how thick it will be on the bottom for sure but I have a strong flashlight and I can clearly see the Roxul stuffed up in there so I'll be able to tell if I get that covered or not. You're absolutely right though, OVERKILL.