When I don't want to top post, I use a workaround.
1) Select and Copy the original email (can either do this in "reading" or "reply").
2) When Replying, Paste the copied text.
3) Click and Select "Delete Original Text".
4) Scroll and answer--I manually add > (or whatever you want) for the original parts.
A bit of a pain, especially when you have to manually add >s...