I'm a huge fan of the original nautilus which was pure mtl (although I consider the larger two airflow holes as very open). The nautilus 2 and upgraded 2s where very good but the zenith/zlide does just tip it for me and yes the nautilus coils have been more unreliable these days.
I'd still look at something with slightly larger coils for use as a small dtl tank. Definitely recommend the old school subtank nano for that purpose (still a very relevant tank that can be used both as dtl and mtl due to coils avail from 0.2 upto 1.5ohms, the 0.5 ssocc coils are extremely reliable) as the coils contain more wicking material which lends itself to dtl vaping. Using the smaller nautilus/zenith/zlide coils with a sub ohm setting and wide open airflow can definitely shorten the coil life as your in danger of drying out the wick quite quickly if chain vaping.