Re: Oh come on!
"nerd and geek have already been reclaimed"
You reckon? If I wanted to insult a nerd, I'd call him a "geek".
But boffin has never been, to my mind, a direct insult.
It implies "not one of us", eccentricity, focus in niche areas, otherworldliness, possibly obessiveness, but not necessarily unpleasant or having a grating lack of social skills.
Geek and nerd still imply people you'd avoid on the bus. A boffin would be quiet company, looking out the window and puffing reflectively on his (unlit) pipe.
The boffin par excellence is Barnes-Wallis.