Mine seem to last forever. I leave the tops off and drip them to keep them wet. No cartomizer gets constant use because I have maybe eight or so flavors going at a time, so that throws a wrench in my impression of carto life, but I have yet to have a carto die on me.
Absolutely. I lost a soft cap somehow and afterwards, just vaped without the cap. Performs much better now. I've read somewhere here that the new cartos work very well with drip tips too.
I've been using the hard tipped blank 510 cartomizers from Litecigs since about the middle of last month. So far I've had 11 in rotation between active use and cleaning/drying cycles. Out of that 11 one died completely a couple days ago after several use and cleaning cycles. I've shelved 3 others for sub par performance. They still work but perform poorly as compared to others.
I'm still happy overall though. I just ordered some more. They are, after all, supposed to be disposable. Incidentally, the very first one I used in the middle of May is still going strong - so far.