I knew a guy whose laptop was stolen and it had a major companies game engine source on it - which was not open source (he had done some contract work for them).

Personally I used LUKS encryption on a system76 laptop for 7 years and it worked fine - still going in fact. I was always worried about it failing especially after an update, but that never happened.

For backups to offline media I still do use file-level encryption though.