The nissin has a stronger GN compare to Nikon SB-600. (Meaning stronger flash power)
SB-600 would be slightly advantageous if you wanna do remote flashes. (Nikon CLS)
I had mk1 b4 but I do not trust it's i-TTL. Not too sure abt mk2 though.
ecurbw said:
FP is fast speed sync. BL is balanced lighting and is used when filling in with bright background.
I don't think it's just for bright backgrounds, I think it's supposed to balance the flash with the ambient light. Or at least that is what the name suggests
if got more budget then better choose nikon..
my Nissin di622 defect within a yr.maybe my luck no good