Been using these batteries for over a year, and have recharged them many times. Quite a bargain, compared to disposable batteries. Not all devices are Nimh friendly, and really need the extra 0.3 volts per cell. My main reason for giving these a try.
Enelopes are low self discharge, simply hold their charge, when not in use. They make little difference, for things you use often, and average about $2.00 each cell (yeah, brag about all the great deals that can be found).
Rechargeable are about saving money over time, compared to just throwing money in the trash, with single use batteries. You have to swap them out, recharge them, more frequently, than just using disposables, same with any rechargeable.
The charger is a 'smart' charger, used both, the 4 position, and the 8 position, each cell is independent, and most definitely not on a timer. Besides, how could it do NiMh batteries as well. I've only had a few batteries fail, in more than a year, over-discharged them. None have leaked, in the charger, or device. Batteries barely even get warm in the charger. You get hot batteries with timer based chargers.
When you over-discharge any type battery, you run the risk of leakage, and a good chance it won't charge again. You can't run your device, until it stops working, before changing the batteries, like disposables, since you will be disposing rechargeable just the same, but at a higher price. Need to learn new habits. I just sometimes forget which devices have disposable batteries sometimes.
It's better to recharge batteries, before they actually need it, rather than wait too long between charging.