I have a subtank with a 1.8 ohm coil in the RBA deck. Works fine. The Kanger Subtank is capable of going to 0.5 ohms or less (I forget if there is an exact number because I don't go below 0.5 myself).
The thing is that there is no free lunch with the juice. If you want more vape than the Nautilus Mini gives, you are going to burn juice to get it. So the subtank will probably burn more juice no matter how low you try to throttle it, but it will probably always put out more vape too.
Personally I chain vape all day, and I burn about 10-15ml of juice a day. I make my own juice, it costs me 3.5 cents per ml, and I've never tried hard to throttle the subtanks back. If I bought juice I would be concerned but then again I would be concerned about vaping anything beyond a Nautilus, I guess. I've put a lot of effort into getting to a place where I'm not spending more on vaping than I did on 2-3 PAD of cigs (at $3/pack most of the time).