Mike, I prefer the mechanical mod...especially the Reo. The spring will drop, in case of a runaway. After using them a while, you get a feel for when it is getting low enough to charge the batteries. I switch batteries twice a day. Invariably I nail it pretty close to 4.0 volts, or 3.9 volts. It is very rare if it gets to 3.8 volts. I can tell when it gets on the low end. The preferred battery for a Reo is an A&W button top. I use the 1600 mAh. A lot of people like the RM2 atty. It is a very simple, yet very effective design. I have a Derringer bottom fed clone on mine. I also have a Quasar atty on my Metal LP Reo Grand. It is very good too, but I would NOT put that one on the Woodvil. The newest metal Reo he has seems like the best of all worlds to me. I love the Woodvil, but I wouldn't dare take it out of this house. That's what the metal Reo is for.