Are you expected to work roughly the same amount in 3 or 4 days in this scenario? If so, it's not a draw for me (lots of employers let you just put in the hours when you want outside of meetings anyway)

If by 3 day work week you mean you're expected to work roughly 60% as much for 60% the pay, then yes, I'd be interested (but I'm not the person you replied to)

Startups can always compete on equity if they so choose.

yes