New Fed 5b on ebay

OK, Other than being a rather tall camera I would think the newest Fed 5 series would have been the culmination of everything fixed that was ever wrong with the previous models.
Of course things don`t always go that way but I`d like to hear what others may know about this model simply because there are some new ones available for some really low prices. I suspect there is a good reason but I`d like to learn what they are.
Thank you,
John

I personally have good experience with FED 5. All 3 what I poses working without any problems. But I hear much different opinion from other sources.