I started with clearos, and was a huge fan of bottom coil clearos, UNTIL I got into carto tanks. At Badittude's recommendation, I ordered an IBTanked carto tank, and quickly bought another. For months, carto tanks became my preference. Easy to setup, dependable, good flavor, good vapor, etc.
About 2 months ago, I finally got a kayfun lite clone. That ruined carto tanks for me. In fact, the kayfun was so amazing, that I ordered an Igo-W5 dual coil dripping afterwards....and now I can't vape ANYTHING besides RDAs and RBAs.
With adjustable airflow, the Nautilus is at the top of the clearomizer food chain. It would be a difficult task to find a better clearo.
I would go ahead and order the Nautilus if I were you. I don't see any reason why you can't use the Nautilus, AND carto tanks. Afterall, I still occasionally use my IBTanked carto tanks.