Now - are you talking absolute or relative to the design of the 'Logans? Most have a slight backwards tilt, but I rake mine a little forward. I still answered "Slight backward tilt".
Spire- standard is 85 degrees, I have tried from that to 90 degrees, and have happily settled on 87.5 degree panel, it does make a difference! 90 was too 'hard' achieving the best balance is time consuming but necessary..
Better to ask if people have CHANGED the angle from how the speaker is built. So a 13A starts with a 5 degree backward tilt, but the 15A is vertical. Therefore owners who choose say 3 degrees would answer LESS if they own a 13A but MORE if the own a 15A. It would be useful yo know if people increase or decrease tilt from what ML thinks the tilt should be!
I have adjusted the tilt from original of any of the 6 pairs of ML's I have owned. I will depend on your seat height and distance from your speakers to your ears.
I believe you want to be listening to the vertical center of your panel. This way you will receive a more even wave of sound from the entire panel since it will reach your ears at closer to the same time. If you have more forward or back tilt you will be listening to more of the top or bottom of the panel.
I take a carpenters framing square that has one 16" leg and one 24" leg and place one leg against the vertical front of the panel. It is fairly easy to see where the center of the panel is pointing in relation to the height of your ears in your listening position. Then adjust the tilt accordingly.
I only use the square to adjust one panel tilted to focus the center of the panel at my ear height. I then sight the speakers in relation to each other from the side. I adjust the second speaker to have the exact same tilt as the first. I think this is much more accurate then trying to do it with the square a second time.