I understand the altitude issue, and there is value in the Rotax. But even with the Rans S21, where the company owner and designer is an outright Rotax fan, 95% or more of the S21 kits are being sold with Titan 340 engines or mounts for such.
The Aircam is a phenomenal aircraft for its mission, and is designed around the 912/914 engines. But holy man have you priced one?
I’m a believer in both modern technology (EFI, EMags, EIS) and also a believer in cubic inches. But at the end of the day you balance your mission to the value of the chosen engine against your wallet.
I drive diesel pickups, but not for better fuel mileage as that would not offset the purchase cost delta. I drive them for the power, reliability, and drive ability they offer. Those items justify the cost increase.
In a heavy hauling places to go people to see bushplane, the Rotax isn’t my choice, or my wallets. 🤪