I don't have any experience with the Jabiru at all (heck I still
haven't completed my checkride ), but just a few things to be aware
of:

1. Rotax is water cooled; Jabiru is air cooled. Don't know if this
matters to you, but I thought I'd mention it.
2. Rotax runs at a very high engine RPM and uses a redrive to lower the
RPM at the prop level. I know this it is something that you could get
used to, but the 1 time I flew in a Rotax powered plane it sounded like
I was about to blow the engine, even when it was well below redline.
3. At equivalent power levels, Jabiru seems to a smidgeon cheaper.
4. Jabiru seems to have a lot of FWF packages available for different
aircraft already designed and ready to go.

Personally, though I haven't done a lot of research, I'd personally
look more at the Jabiru. Definately don't take