Dave S wrote:

Then why did Diamond dump the Rotax for Continentals?

They initially offered both when the Conti was first available. The
Katana just needed more power. The higher cruise speed and much better
climb rate of the 125hp IO-240 Conti made a huge difference from what
I've read. Most Katanas are in school fleets so the higher TBO was
probably a factor in the engine swap IMO.