The biggest reason I don't want to do the carto tanks is that I don't have anywhere to keep them when I am out and about. I live in the city and use public transportation for everything and I don't really want to carry a bag full of accessories everywhere I go just for vaping. It might be good for at my apartment, but most of the time I'm not here, and being a college student I don't have a desk I can keep them at while I'm out at classes. I don't even carry books to class, just a binder and pen because I hate having a lot of stuff with me. To me it's a bigger pain to carry larger accessories I can't fit in my pockets.
The whole thing together fits perfectly in my pocket, people think its a pen.
Why would you have to carry a whole bag of accessories? you only need to fill up your tank 1 time and you are good for a whole day.
Its a pain to walk around with a bottle liq and have to drip every couple of puffs. Carto tank you just fill it up before you leave the house and you should be good for a whole day. I never carry anything more than my PV around. And its more in my hand than in my pocket.