There's really no difference between the energizer and duracell alkaline batteries as their specs are the same. You can try the energizer e^2 alkalines, they might do a little better, but cost twice as much. The rechargeables would be no good as they only put out 1.2v each, so 2 of thoes would only provide 2.4v and with the laser diode needing the full 3.0v, using these would only give you 80% of the power. So a 100mw laser would only put out 80mw with the rechargables. They would be much cheaper in the long run though, but at a cost of 20% of your output power. My PGL-III puts out on average 220mw or so; that is with new batteries and I mean brand new as since the current draw on these is hugh, it only takes about 5-7 minutes of use to notice the batteries are losing it. After only about 5 minutes the output voltage from alkaline batteries start falling below the 3.0v mark, and after maybe 10-15 minutes of use, I replace the batteries and use the old for my kids toys that don't require so much current. There is something I want to ask you privately, I'll be sending you a PM.
Jack