I love tanks with cartos, BTW the one you ordered is a tank that came with a CE6 not a regular cartomizer. Anyhow, I have been using carto tanks for 6 months now and have only had one leak. It was a smoketec and it was slippery and cheaply made. I got a phiniac next and it is flawless. I have about 10 carto tanks: IBTanked, Valley vapes, Kir Fanis etc, NONE of these leak.
Like elmattias says, they are a container that hold juice, they do not affect your taste or performance ( only if they are not airtight, or loose) carto life depends on your juice, the ingredients in your juice ( certain tobaccos can clog them up ie NET tobaccos) and how many ml you put thru them) Also lower wattage/volts also affect the performance of a carto. I was having problems with life, but once I got my PV kicked and upped my wattage they are much better.
I use RTAs and the flavour is better or the same as my cartos and on a couple of my juices they actually taste better in my carto/tank.