Tidy Cat Breeze Question?

First of all, I have to start by saying I LOVE this litter box, it has nothing to do with the time it saves, as cleaning litter if kept up on does not take long either, but I LOVE it for the smell reduction (I kept my litter box extremely clean but that room still always smelled like cat litter) and for the litter not being tracked all over my apartment.

Ok now since I'm done raving about this product I do have a legitimate question, one thing that I don't like about the breeze is that the pads are almost impossible to find...so I was wondering could I substitute puppy potty pads for the tidy cat ones. I was thinking the Arm & Hammer Puppy Pads as they look to be the same thickness. It is okay if I changed them more often maybe twice a week versus once. Has anyone else tried these? How did you find it worked.

Also, another question I have is has anyone tried use two bags of pellets in the box at the same time? I think it looks awfully sparse in the litter box with just one. I know they say it is not supposed to be as full as normal litter, but seriously once my cats are done pooping in the box and moving the pellets around there is all these bare spots...do you think it would make any difference if I stuck two bags of pellets in there?