The only time I've had a flooding problem is when I punched one too deep and it punctured the inner "sock". I personally haven't found the hole or slot size makes much difference for my normal 70/30ish blends. I honestly don't measure my pg/vg. I have a 250ml bottle that I got from my friendly pharmacist and I fill it with half pg/half vg. I use pg nic, some of my flavorings are pg, some vg based.
I do like my dremel, but my ole geezer eyes have a hard time seeing in the poor light in my MIL's basement...that's the reason the saddle valve is easier for me. On a sunny day I can plug the dremel in outside for better light.
Faa...be sure to pre fill your carto before you put it in your tank, and after you fill the tank, let it soak to saturate it good...20 minutes or so. You may screw up a carto or 2 at first but you'll get the hang of it really quick