gas on demand vs electric on demand

[Punatang]

was wondering if anyone had a gas on demand water heater and replaced with an electric on demand water heater, and if so how much electricity did it use per month vs gas per month?

I have had both and unfortunately it's really difficult to give you an accurate comparison on operating cost which is what I assume you are asking. The gas ones definitely require more maintenance and patience. The other poster is correct though that less work from the trades is required as you don't need 220 volts for gas.  If you buy a cheaper gas one and you are not handy, you will be paying servicemen to come do some really minor things in the relatively near future.  Good luck making the choice and enjoy that hot water!