Ask HN: Has anyone used Mashery to manage their API?

Has anyone here used Mashery (or any similar service) for managing their API? For a small startup, are there any major problems that Mashery could help solve/avoid? The pricing for startups is arondd 500 bucks/month, so its not cheap. If the Mashery infrastructure sits in front of our own API, I'm not sure I understand how it can really manage load or performance issues, especially if there are underlying problems in our own API? Thoughts?