I've a chance to buy a used 60 series Metz flash for around $250. My thinking is , I can use this for 6*6 and 4*5 hand held portraits under a lot of diverse ligh t condtions. I've got two questions: first, is there some reason that pros drop these on the market because of some problem the unit develops. Is a used Metz a liability. Anything I should know about looking at one? Second, is there a good book that covers the creative use of this flash. I shoot mostly black and white, only a little color. Does this flash work with daylight color film? Thanks.