It can do coils down to .5 Ohms, but it will run them less than battery voltage since the limit is 15 Watts. For example, it would run a .7 Ohm coil at 15W which would be 3.24 Volts. You would get better performance with no Kick in there.
I'm sure getting a 15 Watt output out of such a small device took some doing on Evolve's part. I'd be surprised to see it go higher than that any time soon. Power output takes circuit board space which is a high premium for the Kick.
Because the circuit board is so small and there's little area for heat dissipation, running the Kick at its limit may become a reliability issue. Just have to see how they hold up when people start using them.
There's advantages to higher power output even if you don't use it. It provides better efficiency and reliability since the electronics don't have to work as hard to provide the output you do ask for.