I think I will change the design a bit though.

After looking at the Klipsch RS-62, I think it makes more sense to have a complete set of drivers on each side.

I will use two Monacor SP-6/150PA mouted in a 14-16liter bass reflex triangle shaped cabinet, that should give me a F3 of about 75hz.
For the compression drivers I think I´ll go with the new BMS 4524, it can be used down to 1900hz and is still very cheap.
The horns are not yet completely decided, but something nearly square with a 90x60 pattern is fine.

After thinking it over again, the dipole arrangement makes NO sense at all when using horn. I´ll just wire them as you suggested in a bipole arrangenment.