I think it's useful to think about the same way you think about test specificity. Ie, of all the people in the world that hit this page, how many of them are go

I think it's useful to think about the same way you think about test specificity. Ie, of all the people in the world that hit this page, how many of them are going to need this feature and use it correctly vs. how many don't need this feature and accidentally use it. Using the Escape key is fantastic for "I needed this feature and it worked", which is probably 1 in 100,000 users of the page. It's terrible for "I accidentally used this feature I didn't know about" and that's the other 99,999. All your other suggestions fail for this reason too - you need a high level of confidence the person really intended to escape. I for example would mash the space bar three times to scroll down.