Thanks for the response. We’ve replaced Tim Thumb with custom thumbnail sizes in as many places as we could, but it is still needed in some of our sliders where the image size is dynamically set based on the number slides used.
Is there an API or some way to access the W3TC variables for the s3 bucket name that’s configured for Amazon S3 origin push? That way I could build the rest of the URL out from the wp_postmeta table before passing it to Tim Thumb.