African Mahogany is a harder wood than spruce or cedar. Harder woods will have a break-in period where they are brighter when you first get the guitar and, as they are played, they mellow out and you'll notice more of the deeper tones. Volume levels seem to be on par with spruce tops but with less attack.
The auditorium body shape is probably the newest body shape for acoustic guitars. The auditorium takes elements that players love from various other shapes and combines them into a single body. The sound will be slightly different than a dreadnought and will scoop some of the mid range but it maintains the full dreadnought sound. It has a skinnier waist, much like a grand concert. This allows the guitar to rest lower on a player's thigh when sitting down and does not put as much strain on the shoulder. It's not hard to see why auditoriums have gained popularity so quickly.