Did you ever get down to trying fumaric acid? How does it compare to citric and malic acids?
I've added an update to that post: http://www.jefftk.com/p/citric-acid
I ended up ordering malic and fumaric acids as well. I like the malic acid a lot, but the fumaric acid is really hard to taste. Not being soluble in water it just sits on the tongue being slightly sour. I probably just haven't found the right use for it yet.
If you want people to ask you stuff reply to this post with a comment to that effect.
More accurately, ask any participating LessWronger anything that is in the category of questions they indicate they would answer.
If you want to talk about this post you can reply to my comment below that says "Discussion of this post goes here.", or not.