i have a 2200 watt element- i only fill the 50L boiler with about 25L and the heatup time is about 45mins. 2 element will reduce ur heat up time, but since you will turn one off while your running it, it all comes down to how patient or impatient you are. I usually put in the wash and turn it on, by the time i put the still head on, get the hoses out etc, pour a drink etc, its on it way to heating up.
There is a temperature calculator-
http://www.aussiedistiller.com.au/xcalcs.html