Other than my infamous dislike of DefTech...
I would ask why you have them diagrammed so far apart?
What are your overall sound goals? 5.1.x? something different?
The key to a proper HT is that basic 5- or 7- channel Bed Layer. If you cannot set that up for yourself, then nothing else will work quite right. That said we all have to work with what we have and I am no different.
But right now I see no mention of Surrounds, and putting any Height speaker with only a 3.x.x arrangement will likely disappoint.
Can you elaborate please?