Hello,
I have the honor to be the Captain of the first Production Legacy 450 (serial #3 - 1 and 2 was test aircraft then sold). I fly it for 15 months now and a total of 400 hours. It's the best aircraft of his category and on every aspects. Beside the latest Gulfstream, there is no better cockpit : wide, ergonomic, silent and efficient. The cabin is plebiscited by all passengers (both Charter and Owner) including pax used to fly Falcon and Challenger. The Hold is huge and the internal stowage compartment is so useful. Of course the Galley of the 500 is better but the ration price/performance is better with the 450. We are operating quite often in the south of France at St Tropez airfield (1100m) and are the only mid-size aircraft in the world able to do it. Just qualified to London City. To Fly by Wire system is a must and so easy to fly even with strong and gusty cross wind.
The biggest default for me is the range. I would expect to fly direct London - NYC or Pars - Dubai. It miss 400 NM.
Regarding Mx, no major issues and the Embraer Service Center is doing a great job gathering the fixes from all around the world. Of course the Mechanics don't have much experience on type so it takes a little bit more time to fix the problems. We had 3 AOG (pitot, wx radar, fire loop) since delivery and all fixed in 48 hours.
Feel free if I can help with more questions
And you can check this video :
https://youtu.be/Zfh6dC5Eghg
Regards
Cedric