Best answer by gregtommy
As far as is it worth it. I will tell you the answer for me is yes. I am a sonos addict and I have 14 sonos speakers spread throughout my house and I started with a 5.1 setup. My reasons for running with Sonos is I am an avid music listener, I enjoy the surround sound for movies, but I also do enjoy cleaning a house having all the speakers going and being able to walk into every room hearing clear great sound. I don't have to worry about cleaning in a space that doesn't have music playing. I even recently expanded with speakers in my garage so when I am working on my car I can be listening to music. The 5.1 system is an investment, I have play 1s and if you were to go bigger you would get more sound, but my argument for the play 1s are your satellite speakers are meant for subtle noises and to add to the environment but not to blow out your ears from behind. Besides that I don't believe you are getting that much more by design since a play 1 can put out the sounds your are looking for from satellites in a smaller form factor and a cheaper price. Only you an make the decision on what size to go with but that's my 2 cents.
I will leave it on this, the difference between sonos and everyone else is Sonos makes smart speakers, you get a receiver, an amp, the speaker, all of the services sonos offers all in one well designed package and it is pricey. With all that if you have the expendable funds I would recommend getting the sub and remember sonos does have a 45 day return policy so keep that in mind. Good luck