90 degrees really makes a difference.

[wensean]

Does anyone listen to Martin Logan ESP make its surfaces 90 degrees vertical to the ground?

 

[Duke]

I agree with trying that whenever you deem it a possible benefit. In many rooms a rake is necessary because the height of the speaker panel in relation to your listening position ears is a requirement. It may require the speaker be elevated as needed on a platform.
This is just an opinion of mine and I am not as technical as many of these other members.