No, do not use CR123A batteries. Those are not 4.2V they are 3.2V and they tend to explode. I've heard at least three reports of those batteries putting people in the hospital when used in an e-cig mod. People stack two of them for higher voltage and then the cells blow up in their face.
The highest voltage you can get out of a single cell is 3.7V from a Li-Ion cell (4.2 volts fully charged, 3.7V nominal). If you want higher voltage you have to stack a couple 3.7V cells and use a regulator to drop the voltage to your preference.
If you want to improve performance with a single cell without using a regulator, lower atomizer resistance.