answer: not worth.

advise: look into 580ex and 600ex


Sometimes, the Nissin flash will misfire too (the photo turn out very dark)
i think this somehow Might cause by your bad setting, if during group shooting, you tried to increase DOF using F8 and lower ISO to low down the noise, causing the flash to go Fullpower, then you need wait a good 6-7 sec for next fire... else your capacitor is not fully charge/cycled, you end up with a dark frame with half power flash(or lower power). So you need to learn to balance your flash power use, using higher iso or F4 so the flash power can be reduce, so it will improve the cycle time.

F4 @18mm on APSC actually gives you a decent good DOF, (cant say for sharpness because IF you are using 18-55 then the sharpness is questionable).