Here's my take. XLR or balanced connections include a third wire so there is a hot(+), negative(-), and ground. In addition, there is typically some type of signal booster or mini-amplifier at the XLR output stage that boosts the low-level signal from the standard 2volts (via RCA or single-ended connections) and doubling it to 4 volts.
This 2 volt boost and 3 wire configuration is intended to sustain the signal for much greater distances before signal degradation occurs.
The potential negatives of XLR connections is that these little signal boosters or mini-signal amplifiers can inject new or raise existing signal distortion levels and thus degrade listening pleasure. With better equipment, this typically is not an issue.
The potential benefits include allowing for greater cable distances and usually a small boost in macro-dynamics and bass punch.
-IMO