I don't have any pictures just trying to understand the likely impact of thinner nickel on other performance aspects if we trial this is a solution on a larger sample.
From what I have been googling, a thinner nickel layer could be beneficial but at the risk of increased black pad incidence, also a higher P content can help ductility
http://www.atotech.com/fileadmin/pdf/papers/el/Properties_of_High_P_ENIG_process_on_Flexible_boards.pdf