[nerdy]

This seems like a really convenient way to watch for front-end changes, but how do things like margins work? Will my whole page be red because everything has been shifted around or squished?

Responsive capabilities will really improve usefulness, and the absence is somewhat of a deal-breaker. On responsive sites developers will have to eyeball each change even when using Percy, so checking the desktop resolution wouldn't be much additional effort relative to checking all other resolutions for each page.

On the biz-dev side, if it's going to be a paid product it might be a good idea to start charging ASAP!

[dubcanada]

Based on the screenshots, yes if you changed margin on say body, or something high up it would cause everything to shift and be "red".