All else being equal, I would say No deal. reduction in base salary is a huge thing. Let me tell you why. Lets say you do take that new job with the salary reduction, best case you get that 20K bonus. Now, if you want to switch jobs, most employers will consider your base salary first and bonus second because bonus is not guaranteed. Your leverage or power to negotiate goes down with a lesser base salary. Worst case, you don't even get the bonus (oh we had a bad year u know) and there u r. 20K reduced base with 0 bonus. Your next potential employer wont care less why u took a reduction. They see reduction, period.
I know i m sounding harsh here but thats the reality of salaries these days. I understand that startups might have a little more flexibility but as a professional with 10 years of work experience, I would neverever suggest to take a salary reduction. You just don't know where you will end up next.