A few small points of difference I notice comparing the Cheetah and the Calumet. I feel that any small price difference is inconsequential relative to the amount of service each would potentially provide.
- Lithium battery - the accepted norm for this type of battery is a 5 year life cycle.
- Spare battery supply available at extra cost. (Not currently (31 July 2013) listed by CheetahStand but definitely available, if not from Cheetah then definitely HERE although I'd definitely check with CheetahStand FIRST IF you are in the USA - you coyly don't say).
- One battery chamber could be charged while second in use.
- Any future failed battery could be replaced easily, if ever required, without losing the whole power pack.
- TWO power outlets as standard - option to use 2-to-1 cable and halve recycling time (at your own risk as it's designed for the Godox Witstro / CheetahLight flashes :lol.
- Bayonet-fit cables don't pull out of power pack.
- Claimed 900+ full-power flashes per charge. Apply your own degree of scepticism to claimed number in both cases.
- No in-car charger available. Not exactly vital, I'd personally like to have the option though; to many I appreciate it could be totally unimportant.
- (in the same order)
- Nickel metal hydride battery - the reliable norm for this type of battery is a 2 year life cycle. Yes, I appreciate that they often last much longer - as too may Lithium cells similarly.
- Fixed internal battery with no quick change option.
- Charge or use option - unclear if it could be used while simultaneously charging.
- Any future failed battery would necessitate surgery or replacing the whole unit.
- ONE power outlet as standard.
- Push-fit cable connection may possibly pull out of power pack (see David Ward's note re the alternative Sky Eagle PB3000 from Link Delight which uses similar DIN plugs.)
- Claimed 500 full-power flashes per charge. Again apply your own degree of scepticism to this figure!
- In-car charger included.
With those points in mind, I know which I would spend money on.
Both are, like the Sky Eagle, Chinese-sourced but both come with impeccable after-sales service so no worries on that score - the Cheetah service is especially
highly regarded by members here..