Yes, you have a point that the 190 has not yet flown, and yes, some unforseen major problem may crop up but...
The 190 engines are from the GE
-CF34 family that has a tremendous number of operational hours: A-10, S-3, CRJ-200/700/900, E170, etc. (by the way, much more experience than the BR710/715 family.)
The 190 has 89% commonality with the 170 which has been flying for over two years and will be shortly going into service with US Air and Alitalia.
So, with the above info, you can see that there isn't a whole lot of risk on the technical side for the 190.
As for the better performance:
- The 190 will fly approx. 800 nm further at a higher cruise speed than the 717.
- It will also be over 7,000 lbs lighter so it will have lower landing fees & air navigation fees.
- The cabin is not only more comfortable due to the 4-abreast 18.25" seats (with NO middle seat) and wide aisle but it also allows for faster pax deplanement and boarding for shorter turn arounds.
The above is not a criticism of the 717. As I said in my post, the 717 is a fine aircraft but that the 190 is a more modern design that is optimized for the 100 pax market.
Nationalism is an infantile disease. It is the measles of mankind. - A. Einstein