Thinking of getting a 912iS

Advantages to 912is...

No Carb Heat, No Carb Icing.
No Choke.  Turn-Key Start.
No Vapor Lock. The High-Pressure Fuel system constantly recirculates cool fuel.
No Mis-Fueling Accidents. The Recirculating fuel (0.5 Gal/Min.) will cause an on-ground engine failure faster than you can Taxi out.
No Carb Sync. Single throttle body.
High reliability.  Dual Ignitions Powered By Dual Generators. Dual Fuel Injectors per cylinder.  Like having 4 carburetors on a ULS.
The ECU will notify you of any malfunctions in real-time and correct the issue. You won't discover the problem at the start of the next flight.

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That " ... special and expensive equipment to download that ECU data ..." only applies to your first engine and only if you will be doing your own maintenance.
The same BUDS Software can be used on subsequent  'is engines including the 915is if one is in the future.
If you use a Rotax Certified Technician for your maintenance, he should have his own Dongle.

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The price difference is not as great as it appears.
The 912is Includes the Engine Mount.
The 912ULS Engine Mount is a $1200 addition.

Less than a gearbox recondition.......

The IS Engines start quicker and easier, never have carb balancing issues and therefore are easier on gearboxes.

I have both, like both, But if money was no issue IS always

as regards the Dongle, we have one that we share between about ten of us....

I do not know why you would each need one ....sharing maybe not a thing where you live....but here we have a tradition of only buying one and then everyone borrows it, whether it is a trailer, or some expensive welder or other tool ??

The software is really very poor and they need to upgrade it.....but there it is...

Thank you all for your help and advice.  You guys rock!  Since it will be just me, I won't have the opportunity to share a dongle.  Who makes the best ones?  Where is the best place to get one? What is the average cost?  

The only place is a Rotax service center $1600.

I like simplicity,,,,carbed 912's. Both 100 HP and both get you to where you are going. Like Chevy and Ford's. LOL

BUDS ECU Reader 3  ~ $1350 

Let's put this in perspective...
It is about the same price as 100 hours of fuel (400 Gal.) if purchased from your Local MoGas Station or ~65 hours (275 Gal.) from the FBO.
As a one-time purchase, is this really a deal-breaker in the Grand Scheme of things,?