Mono is used only to save the poor postal worker's back. And Amir's too ;)
I have tried listening/comparing in mono. It is no fun business (as it should be!). My main problem is positioning the speakers, especially with short listening distances around 2 m. When I used my living...
I am still learning to use Akabak/Abec for my hunt after the perfect solution.... at least regarding directivity.
Step one is a project similar to Genelec's W371A. Not as tall, but using 14" and 12" too.
I use my Lambda Nova Basic + SRM-xH (yeah, the old 'n cheap one) almost for everything, electronic music included. Not perfect, but not too far from it!
Measurments by Oratory1990 show a fr somewhat near Harman's