Summary: I own a Quantum turbo. Quantum turbo is very powerful unit. However, I have to make sure that I use it properly and charge it a night before the day I use it. Since I have the CP-E4, I always bring it with me and sadly forget about my quantum turbo :( The CP-E4 is a powerful battery units. I can use it with rechargeable AA or regular AA (just make sure that you use 8 of them the same type) The cable is much softer and more convience when I hook it up underneath my 1Dmk3.
Pros: Consistent Output, Durable, Easy To Use, Fast Recycling, Lightweight, Powerful Output, Versatile
Summary: Battery pack holds 8 AA batteries and plugs into your canon flash unit. Works as advertised, cord is long enough and fits well on a belt, or attached to the camera. I really enjoy using it when shooting events.
Summary: The CP-E4 has been a great alternative to more expensive battery units for my speedlites. An absolute must if shooting a large number of shots requiring flash such as a wedding reception. Recycle time is very good, I also found battery life to be great especially with good batteries (I took a recommendation on the eneloop batteries and they work perfect). Unit is lightweight, easy to carry or add to belt.
Pros: Good recycle time, Good Value, Lightweight, Reliable
Summary: Extremely valuable for any event shooter, particularly dark venues like wedding reception halls. It exceeded my expectations, which is to say that indeed I could fire bursts of 3-4 shots at or near full power without a problem. I got it at the end of the season with only 1 wedding to go, but it did really well. The pack lasted all through the reception, and I intentionally hammered multiple shots to see how far I could push it.
Pros: Charges Quickly, Good Value, Long-Lasting, Reliable
Summary: Have suffered for years from the slow recycling rate on internal and external flash units for my D-SLR. This product eliminates that signifcant drawback. It is analogous to switching from a muzzle loader to an automatic rifle in terms of flash recycling capability.