'guys' is gender neutral in the US. 'boffins' is not used at all in the US, and sounds vaguely offensive, even if its meaning is not.
Well that is bizarre. When did guys become gender neutral in the US? How did that happen?
At some point in the last twenty years or so. I can perceive the gender of the term. However, my wife is much younger than I, and she and her female friends exclusively use the term "guys" to refer to themselves and cannot comprehend that I can perceive gender in the term. I mean, intellectually, they know it use to connotate gender, but it is silly to them in the same way that it's silly to us that strawberries are berries that grow in straw. In the US, and apparently also depending on your age, "guys" is gender neutral. And as a hobbyist linguist, "we do not prescribe language, we describe it"...
As a hobbyist linguist, do you have any thoughts about how it might have happened?
Honestly I think it's just a matter of a younger crowd being exposed to the term only in its gender-neutral form, and seizing on that use.
Started exactly in June 1985. In the film Goonies, Sloth called out 'hey you guys' to a gender mixed group. Never been the same.
My comment was mostly in jest, but to address one point seriously, 'boffins' is fine, if nowadays rare, in British English, and since Reaction Engines is British company, its use would be completely fine here.