I think nautilus 2 is best tank for MTL for drop in coils. You won't really get better unless you build.It could be your coils, are they authentic? I too find that the 0.7 coil has good flavor, but if you haven't tried the 1.6 coil it is the perfect balance between the hard draw of the 1.8 and the flavor of the 0.7 (IMO). Airflow and wattage are really important for the Nautlius 2, as it's such a small tank. You can certainly use triton mini coils in your Nautilus to see if that helps, but honestly if you prefer the Melo III for flavor, then you do. It's not a big deal.
If you are getting dry hits, it's a sign that something isn't working wicking wise? You could try a lower PG but I run MAX VG in my N2 tanks (I am sensitive to PG) and I'm able to make it work. I do that by consistently drawing more air through the drip tip AFTER I've inhaled my vapor, to consistently wick juice up into the coil .With this method, I don't get dry hits. Certainly, there are some better flavor tanks than the N2, but some of them are very expensive. To be fair to the N2, for the price and what it does, it's a rather nice little drop-in coils tank, but if you prefer the flavor of your Melo III, after you sort out getting your N2 functioning correctly, there is no reason not to return to that tank if you prefer it.
Best of luck,
Anna
I think building is better as you won't get defective coils like with a factory coil tank