You absolutely cannot listen to an on-wall unless it is on the wall. The on-walls are designed to take advantage of the wall for acoustics. I nearly threw my M2OW away when I first got them because I fell into the same trap. Then I put them on the wall and the rest is history.

As for imaging, on-walls can soundstage and image better than bookshelves and floor-standers but they need to be positioned correctly with respect to your listening position. My M2OW are a shining example of that. Their imaging and soundstage is better than any speaker I've had in my living room.

The M80OW are indeed ported. The port is on the bottom. Just like every other on-wall.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated