For some weeks i use the GATA rta from QP-Designs. It is a single coil rta wich comes with DL & MTL setup and one base. You just change the complete glas with cimney and mouthpiece fron DL to MTL.
I pers. run it fully open (DL) with a 3mm Alien Ni90 coil at 0.18Ohm. The airflow is slightly restricted(not to much) but the taste is fantastic i can say.