Just a quick response to DM's last post.
From my experience, setting the azimuth at or near perpendicular improves coherency, speed, soundstaging, etc. There is also less "blurring" to the overall image. As a general observation, the music is more "up front" and impactful versus a more "laid back" sound with the panels tilted back. Using the old classical music hall seating analogy, think Row D (more vertical) versus Row R. Some will like one over the other but if you have the panels tilted back, you should try closer to perpendicular to see which you prefer. That's the nice thing about ML's. They will clearly sound different when adjusted either way.
Goat, all things being equal, the speaker will sound better if it is more stable thereby decreasing panel / cabinet vibrations. I'd find the best location for your speakers using the sliders, and then install the spikes. Make sure they pierce the carpet and are seated into the subfloor.
As far as azimuth consistency, two ways to do that I'm aware of. More expensive. Buy a laser level. Really cheap, make your own "plumb bob". Attach a string with a small amount of weight at the bottom in the exact same spot at the top of both panels so it hangs freely. Measure the distance from the string to a fixed point (again the exact same spot for both speakers) at the bottom of the panels.
Both of these adjustments can have a substantial impact on the sound.
Good luck.
GG