As a trainer, the Continental-powered DA20 is awesome, so much more inspiring to a student pilot than a C172. And yet I’ve only ever encountered one - one! - in flight school use. I’m sure they’re out there and I just haven’t encountered them. As you say, with a modern Rotax engine it would be even better.
As a private, traveling machine the DA20 has two issues - fairly severe ones. One is that it has no baggage space, just a parcel shelf. The other is that it’s VFR only, and I believe that would be truly cost-prohibitive to change because - at the very least - lightning strike protection is required for IFR certification and the DA20 has a composite skin with no metal mesh in it.