It should act the same as if it was running on a cr123 as long as you use 2x alkaline or 2x nimh. Id becareful using 2xL91 lithiums because youll be 3.4v which is a tad higher than a cr123 and definitely dont use 2x14500 lithium ion rechargeables which would be 8.4v
The head doesnt care what battery it is using as long as it's within its operating voltage range.