Good bit of information there, spider, but what conclusion did it bring you? Up or Down?
Pretty much most dressage riders ride with the spurs down and most are designed that way. I have spurs with blunt rowels and they point down. If you look at most dressage riders they tend to sit with the leg a bit more under and back so the spurs fitted a few inches up the back of the boot will come in contact without having to lift up the heel.
The other thing is that the spurs are meant to be used just under the side and "lift" the horse up to the seat.