We have very different views on how Quirrell reasons... the stakes are a lot higher from my perspective.

Taking him at face value I would expect him to be concerned with the outcome of the wizarding world's fight against the human, thus him and Harry dieing would jeopardize that fight (there is no one else that seems concerned, no lieutenants to carry on the fight). So we are talking thousands of lives, from this perspective.

Bellatrix might be able to help the fight, whether she would save half as many lives than Harry and Quirrell, I'd guess not.