I have one. I build all the way down to 0.27 and I am fine (I dont like builds lower than that)
I am pretty sure you can build down to 0.2 and be fine
Make sure you know Battery safety.
But the lower the ohms, there is a little bit of wattage drop.... Riptrippers talked about it in his review of the
sigelei
EDIT: Quick google search pulled this
As far as amp limits the Sigelei 150 has a 40amp limit