BUDS dongle VS Peak PCAN USB adapter

You understood my point.
It would probably  " ...  be easier to just design a plug-in compatible ECU to swap out...[neglecting] all the liability issues you will be taking on.  " 

Which tasks us back to my original statement ...
" [It will be] ... easier to just bite the bullet and buy a dongle and get on with other concerns. "

If you own one or more of the Fuel Injected Rotax engines, you need to own, or have access to, a Dongle.
Consider it just part of the price of ownership.
The cost is about the same as one year's Fuel Bill, but it is only a one-time expense.
In the grand scheme of owning and operating an aircraft, it is really just a nominal expense.
I understand that it leaves a bad taste in your mouth, but so do many things in life.

You would probably feel better if Rotax sold the 912is engine for $25K with a Dongle included, with the option to save $1k by choosing NOT to receive a dongle.  It would feel like a discount if you already owned a Dongle.

The pricing would be identical, but you would be on notice that you chose to delete a necessary component.
This would be the correct option if you already had a dongle but incorrect for your initial purchase.

I'm with Bill. Leave sleeping dogs alone. I am in my 5th year with my 912iS,(300) hrs and I have used my dongle for fault anlysis and to do the 100hr download of data. When ever I sell the aircraft the dongle will go with it as part of the necessary support equipment. The dongle cost is just one more expence of ownership. Like over $2000.00 to upgrade to ADS-B mode S transponder. I conceede that the cost of the Rotax dongle is way out there when a generic dongle can be had for under $100.00, but it is not unusual for manufactures to protect their propritary data.