With the recent launch of the Nissin Mark 2, several new features have been released. http://www.reddotphoto.com.sg/conten...ark-2-revealed

Comparisons:
Flash exposure compensation
Mark 1: No flash exposure compensation
Mark 2: Flash exposure compensation from -1.5 to +1.5 EV in 0.5 steps

PC sync chord input
Mark 1: NA
Mark 2: Available to connect flash triggers or from camera body with sync chord output for an extra method of triggering the flash

Wireless flash triggering using radio triggers:
Mark 1: Only Di622 Nikon can be triggered. Ni622 Canon has yet to have the firmware upgrade for it to be triggered by PT04 triggers such as the Phottix Tetra/Aster/Strato/Atlas
Mark 2: Both Di622 Canon and Nikon can be triggered by regular radio flash triggers.

Wireless flash triggering via Nikon/Canon flash system
Mark 1: NA
Mark 2: Possible to control the Di622 Mark 2 Nikon via Nikon CLS system with iTTL capabilities. Similarly the Canon version can be controlled by Canon systems such as the ST-E2, 580EXII, or camera bodies such as the 7D and 60D

Price:
Mark 1: ~S$20x
Mark 2:~ $24x

Both flashes are still in production and one has to decide if the extra functions and new firmware is worth the extra.