I'm sure you realize this, but the fellowship goes beyond the scope of having a perfect GPA and tons of publications. I also held a position at USGS for 2 years, completed a NSF REU, worked in my field as an undergrad for 4 years...everyone has a different story. I think that in my case having them to corroborate my IM was very beneficial, but for most it probably just isn't enough by itself to make you stand out. I also think it's acceptable to have a lower GPA in my field. I actually merely listed my conference proceedings/pubs at the end of my essay with citations. I focused more on what I learned from each experience rather than the fact that I had presented at several conferences, published papers...I did find a way to tie them into my personal statement, just was never the focus of any portion of my essay.
My BI section was "the most remarkable portion of my application". Based on my reviews, they take it very seriously.