Typical small room acoustics benefits significantly from a multiple sub/multiple location subwoofer system
approach. By far the two most important elements in audio are the loudspeakers, and their interaction and optimization in the room. Utilizing two subs, one can opt for a selective mode cancellation approach, to minimize modal issues in whatever room axis needed. If the biggest problems exist in the front to back direction, then employing a sub front and rear will pay dividends. Likewise, if the issue is with lateral modes across the width of your room, then spacing them left and right of a median line will yield you the best results.
Ideally, employing four subs can address both axis, and this is illustrated in the AES paper below.
You may enjoy reading this AES paper
by Welti and DeVantier,....it's very good and illustrates the benefits of a multiple sub approach.
All the benefits listed before are true. Better bass over a larger area. More output, lower distortion, less compression, thus dynamic portrayal is rendered much more accurately. All said, the biggest benefit is reduction of modal issues, Thus, better delineation of the subwoofer range can be expected if properly optimized wrt time/freq EQ'ing.
Best of luck