It's weird to compare a bookshelf speaker (m22) to a tower speaker (EMP 5is). The EMP's will likely be able to play louder and deeper. You should compare the EMP bookshelf to the Axiom m22. I think you will find the M22 to be a more impressive speaker.

However, the EMP towers have been getting a lot of high marks at AVS. They look gorgeous and they have RBH Sound people involved, one of the oldest and most respected American speaker brands.

See: http://www.avsforum.com/avs-vb/showthread.php?t=1388934

Also since you already have an Axiom center, it makes sense to keep your front speakers Axiom (as others here mentioned) unless you plan on changing all of your speakers.