The idea behind AideRSS is that you can subscribe only to the "Best" or "Great" posts in a particular feed, rather than getting all of the feeds, in effect, slimming down your reading material - a lot like iTunes' option to buy single tracks from an artist's album without also having to purchase the filler.
According to my pointing AideRSS at my own feed, it tells me that of the 197 posts it found after July 8th of this year, 23% rate as "Best", 47% as "Great" and 63% rank "Good" or better. I'd expect they try to follow a quintile rule, showing a common 20/40/60 tiering. But this grade is obviously on a curve. Given that I often have posts without any comments at all, a pair of comments or handful of external links can vault my post into the "Great" category. I'd venture a guess that the bar is a lot higher for more popular A-List blogs.
Over the last few months, I can't argue with AideRSS' analysis to my top stories, including "What is the Future of MyBlogLog?", "Alexa Web Statistics Show Old Media Influence Nosedive", "Internal Linking On Some Tech Blogs Is Out of Control", Eight Reasons the Apple TV is Failing, and How It Can be Saved and yesterday's "Feedheads Approaching 10,000 Active Facebook Users".
Despite this, I am fundamentally opposed to the idea of filtering my RSS feeds. Waiting for the reactions to already occur pretty much guarantees I would get to the stories after all the activity has occurred, and if I jump into the conversation, I won't be first on the scene to participate at all. I'd rather get all the news fast, make the determination on my own, and keep going. For me, AideRSS just becomes another toy to play with my blog and RSS feeds in general, not a catch-all sieve.