Erick,
the 1050 S3 guys here will speak for themselves because they love them.
I don't think there is anything to worry about the 1050 motor.
Having said that my own ride is a 955i 2004 Sprint ST and I am in love with it.
The 955 has been around a long time and naturally a late model (2004 was the last Sprint) will have the bugs ironed out.
The 1050 makes 5 more HP and is more torquey than the 955 but they are both rock solid, smooth powerful engines that make torquey creamy smooth power from very low revs to the red line.
Over to you S3 boys
DaveM