Emily -
I agree with Stacy on this one. I know it's tradition to use a serif for body copy, but as a government employee who can only use 3 typefaces (Joanna MT, Franklin Gothic, TNR), I use FG the most. I haven't set a large amount of text with FG..more short copy...and it's clean and readable at a small size. Let's face it, these government documents have So Much text that we generally have to go to 8-9 points. I know...ridiculous. So it works for that reason. I am AFRAID to venture out and do large copy with it. I believe it depends on the sans-serif. I personally like it better...because it's clean.
But I find this link interesting---and I'm sure this rule was made for a reason. Hope this helps.
http://www.webdesignerdepot.com/2013/03/serif-vs-sans-the-final-battle/
