Macman, the “annoying peaks above the usable frequency range” is something that your specific installation might have in context of your room and your acoustic system location but it might not be a characteristic of tapped horns. I do feel that tapped horns might be more room picky as the radiation surface is very small in them. In your correct case of dipole it is for sure more room forgiving.
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche