This thread probably belongs in the Lounge.
If I'm following your reasoning correctly, you think that by adding a second speaker (with horns rotated), you are gaining not only 10 degrees of horizontal converage but also doubling the power. Win-win! Not really. You are burning twice as much power (compared to a single speaker), and putting twice as much acoustic power into the room. But you are simply spreading it over a larger area -- most of which is in the verticle plane, probably not where you need it.
Actually, the big qualifier to what I said above is that this only applies for the frequency range covered by the horn. I haven't looked at the specs, but I'm guessing that's only above 1.5 kHz or so. Frequencies below that will suffer from comb filtering --doubling the acoustic response at some frequencies, and completely eliminating it at others.
For best results, if you need to array speakers (to increase coverage and/or increase power), then stick to speakers designed to be arrayed. In other words, speakers which have good pattern control down to much lower frequencies.
