Fuel injection is a good addition, especially for someone like me who has no clue how to work on/clean/adjust carburetor. So far I never had to *knocks on wood*. If I have to use a fuel powered machine, I'm all for efficiency.
Electric. I'm all for it, but in my case battery capacity isn't there yet.
Bluetooth : how to add connectivity where it isn't needed to please the smartphone slaves. If you need your phone to notify you when your machine needs new filters & oil, why don't you subcontract lawn mowing so you can keep managing your precious virtual life ?