Uneven Heat Distribution with Primo

I have a Primo ceramic cooker (small) that I've owned for about a year. I really enjoy smoking on the unit - the diverter certainly helps. When I grill on the Primo, the heat is concentrated in the middle fo the grill as the air draft comes through the middle base of the unit. I move the charcoal around to spread the hot coals, but the outter edges soon cool off. So, I end up moving my chicken\steaks around the grate to try and even out the cook time.

Is this a common issue among kettle, ceramic and other grills with similiar designs (middle botton vent)?

If so, what other charocal grills would you recommend (I already have a pellet grill) that can use lump\briquette charcoal that has even heat distribution.

Thanks