BACKGROUND:I wanted a NiMH AA/AAA charging system that would remove the "mystery-of-the-charge" and provide more confidence in the rechargeable batteries I purchase. So, I did a little research like everyone does (or should do) before buying an item that's intended to last for years (find "The Best (aa/aaa)Charger Guide by John Dziadecki on Amazon - excellent read). I decided to buy two 4-packs of Powerex AA 2700's and two of Powerex AAA 950's to supplement some Duracell 2650's, Kodak 2550's, Energizer 2500's and an assortment of generic 2300's. I also bought two chargers: the MH-C9000 and the MH-C800S.For years I've used an assortment of chargers with idiot lights. I had no idea HOW MUCH of a charge those batteries were getting or whether they really held the advertised capacity. But, it was very clear (and frustrating), that some of these batteries and/or chargers were very limited (junk?). I'm not sure how many times I installed newly charged NiMH batteries into a digital camera only to have the low battery icon show up after a couple shots: "Hmmmm...how many of these batteries are duds?" And, generic battery testers really don't tell you much, i.e., how 'good' is "Good"; How 'low' is "Low"? .....So, it took me a while to get fed up.MH-C9000 Charger:This thing definitely took most of the guess-work out of my rechargeable AA/AAA energy supply. I was able to get rid of six old NiMH AA's in the first week and "rescue" seven others with this charger. The directions with the charger are a little sketchy but, if you know the advertised capacity of your battery and its age, you'll be able to figure out how to best charge it and how many mAh's are available to you afterwards. You'll also be able to determine if the battery is shot. This isn't something you get to do with idiot-light chargers (which work just fine for lots of people). I remain very impressed with this charger.MH-C800S Charger:I bought the MH-C800S to supplement the -C9000 because of its 8-battery capacity. This charger does not provide battery capacity values at the completion of a charge cycle. It does however, have a 16-hour 'conditioning mode' designed to re-juvinate and cycle (discharge and recharge) batteries: it works very well. If you don't care about actually 'seeing' the specific capacity of your batteries, the MH-C800S is a good choice at the right price. It too will tell you if your battery is shot. This charger is all that most people will need or want for AA and AAA re-chargeables.CAPACITIES:I have not used Powerex re-chargable batteries long enough to comment on their discharge rate. But, thus far I haven't seen a difference between my older 2300 and 2700 mAh re-chargeables and the Powerex batteries. It's also too early to determine if the Powerex batteries will last through 1000's of charges.The Powerex AAA batteries have an advertised capacity of 950mAh. They charged out between 956-967 in the MH-C9000's "Break-In" mode. Allowing for heat attenuation, full capacity is about 920. I'll know more when I recharge them.The Powerex AA batteries have an advertised capacity of 2700mAh. They charged out between 2556-2650 in the MH-C9000's "Break-In" mode. Allowing for heat attenuation, full capacity might be about 2300. I'll know more when I recharge them.Some of my older batteries charged out at significantly higher rates than advertised after putting them through the MH-C9000's "Refresh and Analyze" mode: these older batteries are holding charges longer and they discharge more consistently. I can tell that those instances of partially-charged batteries screwing up the camera's current requirement will be fewer. At least now, I'll be able to sort out the weak, lame and starving in the herd.SUMMARY:Of course, there are other ways to do what I did. The Powerex battery purchase was based on the charger purchase: I figured it best to stay with a certain brand and keep the system homogenous. Not necessary at all. The price was right for the batteries and they came with convenient storage cases. In time, if Powerex batteries don't perform well, I'll probably start replacing all my batteries with an assortment of Sanyo Eneloops. I'm in the process of learning what a good rechargeable AA/AAA battery really is.There are several other chargers that perform similar to the MH-C9000 and -C800S: LaCrosse, Sony, and/or Sanyo. Reviews for the Powerex MH- products appealed to my technical comfort level and budget. Good stuff!