Having done some homework on spectrum and which parts of it have what effect on the plants, it's become clearer to me why the initial CDM experiment was unsuccessful.
HPS produces way more light in the red spectrum, which signals the plant to flower, and is apparently the source of much of the 'oomph' in light that plants use to grow. The blue/indigo/UV spectra help with trichome formation but they don't give quite the same signal to the plant to set bud and GROW like HPS does.
Then I revisited the math regarding watts per square foot of my Super Silos, it's roughly 20W/ft². If I added a CDM in the middle of the silo, between two HPS lamps at either end, I might get more yield AND a better spectrum balance. This increases the relative intensity to 30W/ft².
I'll get CDM heavy growth in the middle- but never without HPS from both above and below- and the entire silo should get good blue spectrum augmentation.
I'm just dreaming on it for now, but I'm not seeing a lot of downside. The additional heat is much less than an extra 50% and temps are well under control...