I'm an old timer who would rather use natural light but there are times where a good flash helps. Most flashes have long lead time, a few seconds in between flashes, that you find is too long and you miss the best shot. So a new flash with an option for a battery pack, it got even more confusing. The flash I purchased, Sunpack DF4000U, for my Nikon had the Cannon plug. So I made this purchase praying it would work and it does magnificently! I did a photo shoot with my granddaughter and let me tell you how much they love to take photos'! Even though you can use only 4 batteries, I used 8 knowing it would be a long day hahaha. I was happy that with the faster recycle time of 1.24 seconds I got all those inbetween shots that would have been missed without the extra power from the battery pack. I noticed to that it did get very warm but the built in thermal protection prevented it from overheating. The only con I have is the two flashing red lights, why not green? Oh well, aesthetics not withstanding, this is perfect for me.
I intend to use this for fill flash photography of birds. The increased recharge rate should increase the number of photos I can take, which is important for photographing birds.