Having done some searching around net land it seems as though they are indeed compatible. I would seek futher confirmation first though as I am not being held responsible for other peoples info if something goes wrong
Just as a side note the general opinion is that there is little adjustment in the flash and in general the light they produce is bright and harsh. It is highly recommended that you use diffusers to hold back and soften the light. I also have to add that I have also seen some good results from people with portaflash systems, so I guess learning the system is the key.