You say it drives and steers well, but doesn't feel as planted as it should. What does that mean?
How do you know what it should feel like?
The very first thing the alignment guy shouldda done was air-up/even-up the tire pressure, and the second would be to assess the ride height.
But what both he and you mighta missed was the incorrect scrub radius with the non stock offset wheels, with the tall tires. That usually conspires to make the car hunt for a line, twitching from side to side, requiring constant steering corrections. My guess is the positive camber is transferring weight off the outside of the tire and easing the hunting.
Wait to get a proper alignment until after you have the correct offset wheels on there,maybe a little lower tire height, and the car a little higher in the rear than the front with the front rideheight reasonably close to the factory height.
I shoot for .5*negative camber, and as much caster as I can get which usually ain't much on a stock A. With modern equipment,and working cams, getting the camber balanced is relatively easy.
Sometimes, depending on application, it is better to sacrifice a little camber to get a little caster. But in your case the tech went to +.5 to get 2.7, and IMO that ain't right, and once you get the car leveled front to rear, that 2.7 is gonna shrink. So I highly recommend the Moog problem-solver bushings.