While in-wall and flat on-wall speakers have some shortcomings, the alternative of hanging regular bookshelves on the wall has its share of drawbacks as well when used for HT. This is because most people typically sit pretty low to watch a movie so the speakers have to be mounted lower as well. If these mounted speakers stick out 20" that is not only an eyesore, but also makes the usable space in the room that much smaller. Granted, it may sound better, but there are alternatives from companies who have many years experience.

I have not heard the Axiom in/on wall speakers, but I understand that they use the same drivers, configuration, and crossovers as the M22ti and M3ti bookshelves. The difference being that the cabinet size is much smaller. I would presume that this would be audible, especially in the bass. But I can tell you that the bookshelves are outstanding performers at their price-point and have a slew of online reviews to back them up. I own them with the VP150 for the center and QS4 for surrounds, and I was very happy with them. I have since upgraded to the Vienna Weberns, but those are significantly more expensive as well.