The Jabiru is a great engine. Runs smoother, simple to maintain, and has great power without a gear reduction, multiple carbs, cooling system, etc to worry about.

I investigated my options before spending $20k plus on an engine. Hopefully you have figured out that the Rotax is not the lightest package by any stretch of the imagination, nor is it cheap to operate over a 10 year period. Look at fuel consumption, annuals, and overhauls in the total picture. Reliability is equal since neither engine is causing planes to fall out of the sky. I think the rotax is passed over by those of us that hate a PSRU and high maintenance costs.

OBTW - you can hand prop a Jab in the back country if your battery goes dead.

The single most expensive purchase will be your engine. It costs more than a kit so be careful. Like the plane, you will have to live with your decision. Forget about shock cooling and step climbing. IMHO, anytime you are zoom climbing or quickly descending you are flying unsafe. Just because a rotax handles those two scenarios better doesn't make that sort of flight safe.