I too would hope a male Widney would do a Y-DNA study. Unfortunately, my Widney ancestor is 200 years ago so my Widney cousins are all pretty distant. In the meantime, the following may shed some light on a possible Widney-Whitney connection.
It was related in the 1905 book "History of a Fragment of the Clan Linn" - derived in part from information the author was given by a grandfather who was 6 years old when the family came to the U.S. - that the grandfather's mother Sarah Widney was descended from a Colonel Widney who supported William of Orange at the 1690 Battle of the Boyne. No amount of research has turned up evidence of a Widney at the Boyne. However, two sources relate that a Colonel Thomas Whitney helped defend Londonderry in the siege just a year or so earlier (1688-1689).The sources are: (1) "Derry and Enniskillen in the Year 1689", Thomas Witherow, D.D., Belfast (1885); and (2) "Ireland Preserved; or the Seige of Londonderry and Battle of Aughrim", Rev. John Graham, M.D., Dublin (1841).