"If the senior Navs in the RAF changed their brevets over to WSO, would anyone follow?"
If that's 'senior' as in those who make the cushions damp in dark corners of 4-engined aeroplanes, then WSO = Wee Smelling Oldie... So, unlikely to change to a WSO badge unless matron tells them to.
If that's 'senior' as in quite a few rings to his/her/its sleeve, then WSO = Will Sell Out (for suitable perks, such as a K), so would probably ditch the N badge to look 'kewel' and 'in touch with Our Most Important People'.......