Very good proposal. There are more unicode symbols to choice from: http://www.alanwood.net/unicode/geometric_shapes.html Down arrow/triangle: ▼ It is not only matter of resolution but I personally like bigger fonts and have zoomed in HN so triangles look bad: http://i.imgur.com/fpA7N.png
We could use the "pile of poo" ( http://www.fileformat.info/info/unicode/char/1f4a9/index.htm ) character for downvote instead!
http://blogs.msdn.com/b/michkap/archive/2011/11/17/10238146....
http://www.jwz.org/blog/2012/02/unicode-character-pile-of-po...