I'm a new member, so this is my first post.
Perhaps I am swimming against the tide. I started with cartomizers on a KR808D-1. Great! Until I began to try to refill them. Some were standards, and some were premium cartos. That's when my opinion began to shift. I read up in the forums on the CCFM method. I read also how to remove the mouthpiece caps and clean them. I even saw posts on just dripping very slowly through the battery end and waiting for each drop to go in.
My first effort the CCFM. Some carts, fine! But some just would not uptake much liquid, and despite being careful, liquid would dribble out of the cart cap instead of going into the cartomizer! Hmm. So I checked those carts, and sure enough, they were partly blocked, even though used but once.
So, next step! I tried to pop the caps off of the mouthpiece. Soft cap easy. Hard cap I destroyed two of them, and wound up with three more usable but I would not want to subject them to much handling. Then I boiled and cleaned and dried them. Some cartos were still hard to draw, though a few got better. So I poked a straightened paperclip carefully through, wiggled it, and tested the draw. Like trying to suck a bowling ball through a straw!
Now I have switched to atty/cartridge types. Easy to fill. And if I have to carry four cartridges with me instead of two cartomizers no problem!
So here's a vote for the three piece.
Mega attys and mega cartridges = contentment!