I'm loving my new Nissin Di866 flash.. I bought primarily to shoot off camera.. I also have a couple of Canon 430EX, one is the II version and a Nikon SB-28..
With the 430 EX Speedlites, triggered by the RF-602 (I have three), I can sync at 250th second.. With the Nissin I can only sync upto 200th without any shutter shadow, but on camera the Nissin can sync at 250th..
I have disregarded flash duration being the culprit as this occurs at all manual power settings..
This isn't a biggy for me as shooting in a studio situation at 200th second or under doesn't worry me, and if I shoot outdoors I can always switch to the 430EXs..
But the $64.000 question,, why???