I think our contexts are all different. But, to share a different experience, as an academic (with plenty of conversations involving people in industry as well each year) I have used interleaved and bottom-posting for decades and it causes confusion maybe once a year at most and mostly because Microsoft's online client is broken and at times does not even render anything below "Dear Foo," in the HTML view (got to give this small start up in Redmond some more time though, we can not expect them to implement standards that have only been around for over 40 years).