While I did have both I may not be the right guy to answer your question. You see, I've come to the realization that I'm a mechanic, not a pilot. In the last 15 years I have had a Benson B8M, 3 Mini 500's, 2 Scorpion's, and the 162F. All of them were projects, Better than half were able to get off the ground when I sold them, and I always made something off them to move up to something better. The 162f was the machine I was finally going to get training in and learn to fly. Unfortunately the closest CFI willing to hop in a Rotorway is a days drive away and that makes training difficult at best. While I did get some training and I did get to fly, albeit assisted, I have found I do not have the time or money necessary to devote to flying. I sold the Rotorway two weeks ago.
The Mosquito is another derilact machine that I got a year and a half ago. A deal I couldn't resist that was in much worse shape than I expected. It sat in the corner of my shop till last November when I finally had a chance to get started on it. I have it all back together and running, just mounted the blades last weekend. I need a good weekend for finishing touches and see if it will break ground. Turning wrenches can be done a little here, a day there, eventually it comes together. Learning to fly doesn't work like that.
So, all that said, in my opinion both are good experimental machines but they are very different. The Mosquito weighs 300lbs. and only has one seat. The Rotorway is about 1000 but can carry a passenger. The Mosquito has been demonstrated doing 40ft hovering autos (video on Youtube), the Rotorway's rotor system is way overbuilt, bulletproof, and most guys say it autos better than a Robinson. The stories about Rotorways falling out of the sky started in the 80's and are akin to all Harleys leak oil. There was a time they did but there have been improvements. The weak link is the engine. I was with my CFI in his ship when the engine seized. We were in a hover, he had control, and he set it on the ground, no big deal. $15 grand later he's back in the air. I don't have an extra $15 grand just laying around so every time I got in my machine after that, I worried about the engine and it really took the fun out of it for me. One of the reasons I sold it. The Jet Exec gets away from the engine problem but comes with its own issues that I have not studied.
Not sure how the Mosquito will play out. When it's done it may end up on the market too.