I've noticed a lot of articles appearing on both sites, often within minutes of each other. I want to subscribe to either a Reddit feed or a HN feed to minimize redundancies. I'd rather go with the site that breaks news first, so which would it be? Which site breaks news?
If it's within minutes, does it truly matter? Also, neither site really "breaks" news.
Anyway, to answer your question...
You will probably have to measure it, if you want. Should be too hard. Another, better, solution might be to generate and publish a feed that combines the two, without the redundancies. You could even include links to the separate discussions.
Reddit "breaks news first" for the vast majority of stories, simply by having a much larger userbase. I see HN as being far better filtered though, with higher quality comments and signal/noise ratio.
depends on what type of post. there's plenty of stuff that doesn't show up here or doesn't do well here that shows up on reddit and does well, and vice versa. the crowd is similar, but different.
Anyway, to answer your question...
You will probably have to measure it, if you want. Should be too hard. Another, better, solution might be to generate and publish a feed that combines the two, without the redundancies. You could even include links to the separate discussions.