I have a Nikon D70. I'm looking to go further in skate photography, and purchase a flash. I've been looking at the Vivitar 285HV, and Nikon SB-28. I'm leaning more toward the Sb-28, due to it being a Nikon. Which would you prefer though? Which would work better for an off-camera flash? Which would be easier to communicate with a slave? Which would work better in general?