Based on reading into http://www.bookofspeed.com/chapter1.html, I think it'd be useful to collect data on how frequently page views are aborted before reaching the "onload" event.
Our current instrumentation only sends a beacon to the server if the page load completed.
I recall that the soasta/boomerang approach to collecting Navigation Timing was to send the data either on onload or unload. Which means in some cases that the data is incomplete.
For us, I'd prefer to start with just collecting the fact that it was aborted and after how long. I'd prefer to keep them separate from navtiming metrics for now. Although perhaps we can find a way to integrate it with T181956 later.
We could start the campaign from WikimediaEvents by simply listening for the unload event, and check that navigation.loadEventEnd is not set, and then beacon back based on performance.now() - navigation.fetchStart, or something like that.