I agree the interleaved style definitely has its place, and I do use it occasionally, but I find even with highly-topicalized, technical email it can be helpful

I agree the interleaved style definitely has its place, and I do use it occasionally, but I find even with highly-topicalized, technical email it can be helpful to simply restate rather than snippet-quote -- it's a chance to verify that you've correctly digested the original point, and you have more control of the flow of your message. Of course, like so many things, a lot of it comes down to a matter of taste. (Still, I must defend the honor and right-thinking of top-posters :)