I'll be honest, I'm probably a fan-boy a little bit and I don't know a ton about newer Mercurys or Yamahas. I have a 90HP H.O. Etec on my boat now and also an Etec Skidoo snowmobile.
I like that I can start it with a turn of a key and not mess around with any choke or throttle. Running and idling in a second. I'm sure 4 strokes do that too, but I think its cool to have it in a 2 stroke. Even though its unrelated, the snowmobile is the same way. Lighter and faster than the 4 strokes, same startup functionality.
Winterizing is nice too. Can even go out on a warm winter day and winterize it at the launch quick before heading home.
The only issue I had was software related. I would be driving wide open and it would suddenly cut power and not go over half throttle, even if I punched it. Then it would take off again. The dealer gave it the latest software update and it has been fine since. Took like 10 minutes.