Sub-ohm is nothing to fear. I started in December and have had nothing but sub-ohm devices.
I started out with the subvod kit, and a kbox mini, which is similar to what you've got and what your looking at. I had the desire for more as well.
Now let me correct myself. Between the subvod and kbox, I bought a fuchai and a triforce tank, that rig showed me what vaping could be, so when I got the kbox mini, I was fairly disappointed. Harder draw, less flavor, where as with the bigger setup and more power, I got far more flavor, could breathe thru the tank more or less which equates to more vapor.
But the kbox has adjustability over the subvod so that was a plus. I could squeeze slightly more flavor out of the kbox because I could run higher wattage.
That being said, it all depends on what you are looking for. After the upgrade you seem to be going with here, if you still want more, don't be scared to go bigger wattage or sub ohm. I'm a flavor chaser, clouds are cool, but I want excellent flavor more than anything.
When the day comes for the next upgrade, I can suggest the joytech cubiod mod, it's easy to use, 2 18650 batteries for plenty of power, and will run anyway you want to, be it temp control, power, or their simplistic smart mode. It will run just about any tank on the market.
As for tanks, I'm in love with the triforce, but there are the herakles (less airflow vs triforce) tfv4 (I fought coil life, 3 days was poor) but there are no shortage of options.