I took the original 50K to stay at 33.....bit of a no-brainer as they say. But in those days we - sorry, you - were paying commissioned loadies 50k to stay ffs.
Anyway, I declined the kind offer of 100k to stay in a ground tour for another 5 years - as have most, as I understand it. Excepting those who were always going to stay anyway of course. Would an extra 20k or so - after tax - have swung it? Probably not, as the window for a proper second career would then be almost closed.
To be honest, do they - whoever they are - know who they are trying to retain? Experienced aircrew to bolster the experience levels on the FL? No; I know of guys who would stay for no FRI if they were guaranteed to stay flying. PMA cannot sign up to this. So, we need to retain experience to fill staff appointments. Then what? Another 5 years behind a desk, a couple of OOA, and no (well, less) prospect of employment. Or you pay me £75k to leave, plus 11k a year pension and I can start on my old salary, with guaranteed (yes, the union makes sure of that) pay rises. It may be less exciting flying than in the RAF, but it is flying.
I don't have the answers, but I hope for all our sakes that someone does.