Greater power may or may not offer a 'better' sound. The quality of the power matters also.
As has been mentioned, the increase you are interested in is not really much. However, if you are at the point of running out at your current power usage, it might be all you need.
The issue IMO is not quantity of power, but the quality of the power along with the quantity.
If you buy a cheaper sounding, but more powerful amp, you will be disatisfied with the sound, louder or not.
A good amp can last a long time. My last amp, A Forte 4a i used for 17 years.. and my current amp, i hope to use for the next 20 years (Bryston 4B-SST2)