Atmos speaker recommendations for a Magneplanar surround set up?

Looking to add 6 Atmos height channels to extend my current 6.1 system (4xMG 1.7s front / side and smaller maggies in rear) REL 9/x sub. Using Emotiva Bas-X 13.2 surround processor and enough amplification (Emotiva, Adcom, NAD) to drive anything.

It already sounds pretty awesome and I experimented with centre height channels and now want to install all height channels.

Problem is - I've been listening to various 'highly recommended' <$600pr budget-bookshelf options such as JBL, Klipsh, Kef, Polk. and found them all pretty underwhelming. They do sound distinctly different and some sparkle quite nicely (bright, clean and clear sound) but are utterly lacking in bass. 

Sigh. Should I pick the clearest of the smallest & cheapest of the bunch with a bit of bass below 80hz and let the Emotiva calibration and Rel do the rest? 

I don't listen to ear splitting volumes - it is quite an indulgence already to have maggies for surrounds but the cost and challenge (size) of using them for height channels is prohibitive. I'm open to something like used Dynaudio but is there just no shortcuts with bookshelves? What have others used successfully for Atmos speakers? I can install the 2 rears in a wall but the rest will be mounted on a wall.