Here is a pic of my rear center channel about 3-4" from ceiling and I have run them vertically as well, I couldn't hear a difference tilted or vertical, WAF was for tilted, said "it seemed like they should be angled toward listening area".




Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70