I have results - I'm impressed with the quality of the output - especially that errors aren't cascaded! I would spend more time looking at it now but unfortunately it takes a while to load each screenshot currently. I'll check back tomorrow when your servers have had time to recover.

Do you have plans to support different (user configurable) window sizes? My site uses media queries to differ the appearance based on browser size, which means the older IEs can't help but fail to look the same as modern browsers.

Great work, and good luck scaling it!