I'd have put in an acoustical drop ceiling to make new runs easy .. but that's just me. Makes moving lights in the ceiling around pretty easy too.
Since you're ceiling appears to be 9.5 - 10 ft high I'd probably have added it under the (unfinished) drywall ceiling if heat was a concern, and dropped the cans lights down a bit.. otherwise, you may want to actually let heat rise up and out a bit.

I do not work here, but the benefits are still awesome
Make your sound your own!