Mostly I also believe a carto-tank can be superior.
I don't think people try them for a few reasons.
1) They seem expensive. You need to buy the tank (a good one is like multiple clearos in cost) and then replace the carto. Let us not forget many people swear by rebuilding clearomiser atomiser heads.
True. I believe to have a satisfying first experience with a cartotank you need to use a quality pyrex tank. Better construction and better o-rings. However a good pyrex tank will last a long time; I have some that are over 18 months old. They are made of more durable materials (heat-treated pyrex glass tube, stainless steel or anodized aluminum end caps) while clearos are made of polycarbonate plastic (Protanks excluded). Just the materials used are more expensive than plastic, so you get what you pay for. Pyrex stands up to the tank-cracking flavors; polycarbonate clearos will crack or melt with these flavors.
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2) In many ways (as the famous "Trog" said in the UK) a carto-tank was a kludge. (I had to look that word up on wikipedia and immediately understood.
Not sure I understand.
"A kludge (or kluge) is a workaround, quick-and-dirty solution, clumsy, inelegant, difficult to extend, hard to maintain yet effective and quick solution to a problem, and a rough synonym to the term "jury rig". This term is used in diverse fields such as computer science, aerospace engineering, internet slang, and evolutionary neuroscience." -- Wikipedia
I don't see cartotanks as any of the above. I feel it is a superior wicking system to a clearomizer. Admittedly, a cartotank has a slight learning curve to a clearomizer. That's why clearos are usually included in starter kits; they are easy to fill and use. However, they can be rather inconsistant IMO, often developing dry hits or flooding issues. I've yet to use any clearo brand or model that can make better flavor than a quality cartotank (I've used Evods & Protanks; iClears 16 & 30; and Aspire ce5 & mini Vivi Nova).
I already stated in my previous post in this thread why I believe the wicking system of a cartotank is superior to a clearomizer. The only important aspect with a cartotank is to properly fill the cartomizer prior to putting it in the cartotank. Most novices do not put enough e-liquid in (if they put any in it at all), and then complain the vape tastes burnt. Well, yeah!

You only put a few drops in the carto. Try 25 - 35 drops (depending upon the length of carto being filled).
They are not dirty or messy. They are far easier to maintain than a clearo; in fact zero maintanance other than refilling the tank. The carto will need to be replaced every 1 - 3 weeks (so does the coil head in a clearo). The replacement carto ($2) is cheaper than the replacement coil heads of a clearo ($3).
3) Most basic e-cig users use small (mini) clearomisers... these look right on an e-Go battery. A good carto-tank is better suited to an 18xxx mod.
Not true. There are smaller capacity cartotanks (some made of pyrex) available that look good on an e-Go battery.



2)4) People (well over here anyway) are worried about some of the materials used in cartos. Possible reasons? I don't know.
I don't understand this either. Unless they are worried about the polyfill that is used as the wick material? It's a wick material. So is silica, cotton, Eco wool, etc.