steam-engine.org will give you the exact heat flux.
Less ohms doesn't mean faster ramp up. It means more power. If you put the same power into a coil with less mass vs more mass, the one with less mass will heat faster.
But 0.07 is just waiting to vent. Every time some idiot blows their teeth out or burns their face the entire community suffers for it. You can go over the CDR a little but 0.07 is literally triple the CDR.
The things that can fire that safely are G2, Maxo, Lux, DNA and triple parallel mech mods.
0.15ohm is as low as I'd go on one.