I think you can't miss with the DB8e. It's just more expensive than a DB4e, but the result is all but guaranteed using the bigger one.
The two panels pointed in the same direction show a gain of 15-17dB straight ahead, and as you aim them apart, the straight ahead gain goes down while the gain in the two directions of the stations you want goes up. Not as high as both pointed in the same direction at around 8-10dB, but more than a single DB4e pointed half-way between them. Plus you can add the inexpensive VHF dipole kit to just one of them, for the one channel that would benefit from it, aimed straight at channel 11.
ADTech would know more about this than probably anybody, but what I described is in their online documentation.
https://www.antennasdirect.com/cmss_...s/DB8E-TDS.pdf