@englishmick So you have no problems with leaking or dry hits with the nautilus? and do the coils stand up well to DL?
I have the original Nautilus. I use it with 1.8 heads at low power, around 8 W. Never had problems with leaks or dry hits.
To me it's more of a MTL tank. I've heard the later Nautilus tanks are better for DL.
I also use KFL's and Lemos on the Pico. But I got the impression that you use pre-built heads.
The Lemo is more of a DL tank, at least it can be. It's a fraction too large. The very bottom section of the tank rubs against the battery cap a little, but it works fine.
I like a bit of variety. The KFL and Nautilus tanks have a tight draw. The Lemo with the air flow open all the way and a lower resistance coil around 1.2 gives more of an open DL vape.
There are plenty of tanks that work on a Pico. Anything that's 22mm or less. Maybe 23mm. But I'm not the one to ask. All my tanks are pretty old school.