No, they wont sound perfectly fine. Google "sound localization" and think about where humans have evolved to hear sound from. They will sound like surrounds in a theater setup. The difference is they will be hard panned sounds without front soundstage channels to anchor to.... The HRTF is going to shadow any sound from summing to create a front soundstage. Just nebulous late room spatial cues without direct sound for precedence. frown

I have no business replying.... But I do know laying between two channels as a stereo pair will not sound like a normal stereo presentation. Angled ceiling LCRs would be better, but you will have to think about aligning your phantom image with the display image if you hope to use them for multipurpose.