How does the lifespan of clearos, CE3, Nano, etc. compare to the life of regular cartomizers? I've never used anything but cartos and I keep thinking about taking the plunge and trying some alternatives, but I guess what I'm hung up on is figuring out which type of alternative offers the best combination of simplicity (I really need carto type zero-fuss ease of use) and cost effectiveness ... I have several X2 bats of various sizes - what "carto alternative" would you suggest?