I've found that 2 different citrus cutting methods work for 2 different purposes, and a lot of people don't use the methods properly.
First, is the wedge. Often found stuck in the neck of a bottle or hanging over the edge of a glass, this method is good for extracting juice, which will add a lot of flavor to a beer, and would logically alter the pH. In my opinion, mexican lagers (as well as mexican food) should always come with a lime wedge, but no other beer should get a wedge.
Second, is the slice. A slice should be the complete cross-section of a fruit, and can be very thin because it is used for aroma, not juice extraction. Just float a slice of lemon on top of your pint of hefe, and breathe it in as you sip. Ahhhh