Ok so let me get this straight. How is using the cartos different from using the atomizer + blank carts? The cone is just a cover for the cart/atomizer?
Basically it comes down to this. One piece is simpler, less fuss less muss, and it's harder to lose pieces, the fewer you have. The cartos last longer too. From what I understand, cartos are refillable, while carts are single use. You have to replace the atty every so often anyway, and for the price that's going to cost you, the carto+refill liquid will take you a lot farther in terms of price. For example, a a couple packs of cartridges might cost you $10 (assuming 5 in a pack). Each cartridge may be worth around 6-10 cigs. In the case of the specific brand you're looking at, the price of the cartridges is double that; I'd hope they'd last longer but I don't know. A 15-20ml bottle of refill liquid will run you around the same price, but in my experience, a single bottle lasts me at least two weeks, and I'm a very heavy vaper.
In my experience, most cartos will last quite a while, if you care for them right. A pack of cartos is around, oh $12-$15 (assuming 5 in a pack). Each carto should last around half a pack, maybe a pack's worth of cigs. But the beauty is, as long as you take care not to burn the polyfil (don't run it completely dry), most of them can be reused until you kill the atty. That's a huge savings. That is the basic difference.
Then again, that's speaking in general terms. I'm a bit confused about that specific brand, because I just looked it up, and don't see any atomizer in the starter kits. I don't know, perhaps what they call cartridges everyone else calls cartos? I'd email customer service and ask about that.