What you hear and if you like what you hear depends on your ears, your preferences and your listening circumstances. That being said, I would say adding a Sub would ad bass and so enhance your listening experience. 

at first, I was wondering if sub was only dedicated to home theater. But I understood it can also be used for music only. I know should decide to go with a sub or a sub mini !

One of the nice things about buying directly from Sonos is their ‘try it’ program. 

Same question, except we own the ERA 300 only at this time.  Have a dedicated HT room and much smaller but adequate HT setup in the bedroom.  Like smart speakers for my wife and my work areas.  Previous favorite was the Bose Smart 500.  Tried this one and very pleased after a few days.  Wife absolutely loves it.  Quite a bit of bass punch when placed near a corner in the kitchen and work room. Not so much when try to put it in the center of a table to leave more room topside the the ceiling facing speaker.  I like bass, and wondering if I will try a sub to see how it changes things. Also, wondering if the SONOS mini or the Sub Gen 3 would be best to start with.  I agree that can’t know for sure until I listen in home.  Just wondering what the consensus thinks.  Is the Gen 3 too much for my planned usage?  Thanks in advance. - Mike

That does rather depend on room size, Sub placement, and how much bass you really want. But as so often stated: buy it and try it - take advantage of the home trial Sonos offers. Me: I’d start with the Sub, and only change to the Mini if it was overpowering. 

Thanks for the quick reply!  That was the plan and was working on the WAF cover when I realized the obvious: in the area where I will place the sub there is only one socket set and 1 plate.  Currently have both outlets taken with a small wine cooler and an Amazon Echo sub for the wife’s Echo 15.  Now considering a UPS (line conditioner) to plug the Amazon sub and the Sonos into.  The area where we have the SONOS is a kitchen area.  Funny.  It’s adjacent to the main HT theater where I have to have an electrician come out and install four more independent lines (my main amp requires 2 electric plugs on separate lines.  The universe just will not let me be associated with the “Plug and Play” world much. <g>.  Again, thanks for the really quick response (it is 2:00 am here -- I should have hit the sack hours ago!).

I decided to wait until 2024. There sould be a new Sub out during the year.

I don’t have the patience to wait another year for much, especially with A/V.  If that were the case I’d be buying new gear every year - wait: my wife says I do that now!  If this setup sounds great as I am hoping it will (sounds pretty great without the sub frankly - not dual PS-13 great like in my main HT room but kitchen area great for wife time, family time, etc.) then it should be good for a few years at least.  If something comes out that is light years ahead of this sub next year then I’ll replace it  I did take the plunge and ordered the SONOS Gen 3 sub and passed on the mini.  Also researched a bit and got an AudioQuest - PowerQuest 6 Outlet/2 USB Unlimited Joules Surge Protector (Model# PQ2) with two high current receptacles designed for amps and subwoofers.  Plan to pick up tomorrow and see if I can get it installed tomorrow night.  Will report on the aural results if I am able to stay awake.  Night, guys!

OK.  Got home, had dinner and Unboxed the Sub Gen (3).  Thought it would be a breeze to set up.  It was not.  Took a few tries to get it recognized and after two tries to connect wirelessly had to enter the serial no. manually.  Worked and went to listen.  Did not recognize Amazon Music Unlimited.  Finally, removed the sub and reinstalled.  Then it worked.  Sub is behind a waist high partition between our kitchen and a breakfast bar area, but figured not a problem.  Well, it was a problem.  The sub played but frankly sounded anemic regardless of the source material.  Was turning into a depressing evening.  Then I checked the app, and the sub audio was well below 5 for the sub.  Moved that up to 10 and suddenly went from a light breeze to a hurricane.  This is not a cheap smart speaker system for the kitchen to be sure (especially when you add in the PowerQuest 6 Outlet/2 USB Unlimited Joules Surge Protector Model# PQ2).  But I am very happy with that device and the sound of the SONOS system really is rewarding.  Compared to the Bose Smart Speaker 500, the Echo Show 10 (3rd gen) and the Echo Show 15 with Amazon sub (not renowned for its audio capabilities) we could not be happier.  Sound is superb in its weight class and the WAF is excellent.  Final note: the microphone array for picking up Echo voice commands is almost surreal.  With our other devices we sometimes have to exert a forceful blast to get the attention of the system, especially if the music is at a higher volume.  With the SONOS, my wife really can basically almost whisper the command and the SONOS responds immediately.  Kudos to SONOS for implementation and execution of an admittedly niche application.  We are happy campers.