After reading the excellent M3 Sapphire review I was struck by the 6 degree rake and did a little research and found this:
Tilting the cabinets back will put some speakers in a better position as far as the time alignment of the drivers, but it only works if the tweeter is shallower than the woofer. For the horns, with the sound source farther back, you might need to tilt forward. It's all about the acoustic center of each individual driver and the distance to your ears.
Shallow tweeter+deep woofer=Tilt Back.
Deep tweeter+less deep woofer=Tilt Forward.
This ignores the directional characteristics of the drivers, of course. You might find with a shallow woofer and a very deep horn that so much tilt is required to align the acoustic centers that you are outside of the horn's vertical pattern. Spraying the carpet or ceiling, not the listening position in effect. A separate cabinet (or none) for the horn is often used to allow for positioning the horn further forward without aiming it too far down. Flying them works pretty good though...
So, I tilted my M3TS back 6 degrees, uh, not so great. Then I put them back and put a couple of 3/4" blocks under the back legs to tilt them forward (about 3 degrees, so far).
I had heard about sound "snapping into place", and apparently this is what happened. The good news is that this tweak is free and easy to do and undo. What I heard was only for one listening session so far, so if anyone is interested, report back, good, bad or otherwise.