A typical iron core magnetic ballast uses abt 150w above the 1000w bulb for a total of 1,150watts.
An example is a hydrofarm balast uses abt. 9.6 amps @ 120v = 1152watts.

A typical digital or electronic ballast has a power efficentcy of almost 99% and would use about 10w per 1000w for a total of 1,010watts, plus a little more if it has a fan to cool it.

So the penalty to use a CMH might be worth the better performance it could provide. Dutch needs to do an experiment I think, or may have an opinion on the subject since he uses one.