Sorry John the topic has become a bit messy as my thoughts have developed.
I currently have 3 way open baffles with Saba Greencone tweeters and am looking to improve upon them or replace with improved tweeter(s) either located in the current location or mounted above/beside the panel
I started thinking dipole but in order not to miss an opportunity I am now considering omni directional tweeters like the Elac 4Pi, or front/rear firing monopoles. Anything goes providing it meets the following criteria
Approx 4 ohms
Approx 95 dB sensitivity