(Product Shot taken with Nikon D3S, using SB-900 flash unit with LumiQuest SoftBox 3 under the batteries, and one SB-900 bare unit from above and left. All triggered via PocketWizards.)
Not only does it look cool (coolness is very important to my generation) but it has the performance to back that up! I used to use the energizer rechargeables and found myself disappointed that I would put the batteries in my flash, use them for a few shots, try and shoot the flash again a week later, and the batteries were almost dead. The problem with most rechargeables is that they lose their energy very quickly if stowed away and not used within a few days of charging.
This was THE most annoying thing ever. I have the 20 minute quick charger, but found that it worked very poorly, and needed to be run twice just to fully charge my 2500 mAh batteries. When you talk about mAh, that's the amount of power the battery can hold. A higher mAh equates to more flashes per charge. The Eneloops run at 2000mAh which is still great, but I wish it was a bit higher. They will be releasing the 2500mAh batteries called the "XX" this December. Those may be the perfect battery.
Back to the annoying discharge.... The Eneloops are engineered in a different way (That's all I really understand.) They hold their charge for WAAYYYYYYYY LONGER than any other rechargeables!! So much so in fact that when you first pull them from the box, they still have 80% or more of their charge! Even if they've been on the shelf for a full year. This is huge for photographers that aren't running their flash every single day of the week.
I've found that they run plenty long and actually are always fully charged in one charge cycle. Also, their website states that they run better than alkaline or other rechargeables in cold weather. This is great news as I'm often out shooting in -10 degree weather.
There are so-called "quick-chargers" available for the Eneloop, though I'd hardly consider it fast. The standard charger takes 7 hours. The "Quick-Chargers" take 4.......
Because of the slower charge time, I went ahead and ordered 3 chargers. There are chargers available from other companies that could work well and charge 20 or more batteries at a time, but Sanyo recommends only using theirs and I'm sticking with that. I also purchased about 20 batteries. 20 batteries and 3 chargers cost me $72.49 through B&H Photo. Check them out here: B&H Photo Video Eneloop Batteries
It may seem costly initially. But when you think that 24 alkaline batteries (6 flash sets) which will die and end up in a landfill costs at least $20, your saving a ton. Sanyo claims the new batteries get 1500 or more charges before they die. For the same amount of sets in alkaline batteries, your price would be $4,995! That's a crazy thought! $18.50 for 4 batteries and a charger, or $4,995 for 6000 alkalines, the decision is yours, but I'm all set and happy with my Sanyo Eneloops!