I am assuming by Era 300 set you mean as surrounds for the Arc, or are you getting a separate pair of Era 300s for stereo setup?

Music through a 1.2m wide sound bar will sound different to music via a pair of floor standing speakers which can be placed anywhere.

Whether the Arc Ultra is good enough or better for you in your room that you no longer want to use the Klipsh only you can decide.

You may even find adding the 300s to the Amp as surrounds for the Klipsh suits you and you prefer it to the Ultra.

Thanks for the reply. I am getting the 300s for surround sound. And both Arc/300 for the Dolby Atmos. The Klipsch still found great but my thinking was that the Arc Ultra would surpass their sound quality especially for TV viewing. As I find now that my old Playbar forces me to use subtitles for dialogue clarity. Of course that may be a result of too many rock concerts. 
My concern is that adding the Arc and 300s would sound better overall with an integrated component system. I fear a potential sound “conflict” if I kept the Klipsch. 
I could possibly use them as stand slimes but w/o need t figure out a different set up. 
I hope this makes some sense. 
Thanks again for input. 

The Ultra and kit are great for TV use but it is hard to beat a simple pair of good speakers for stereo listening.

I’d use just the Klipsch for listening to music, maybe add in the Ultra (surrounds in FULL mode) if you have a party where more even sound around the room is more important than a clear stereo image.

Not saying the Ultra is “bad” at music, even my Arc and Gen 1 Beams are decent, just that a hefty pair of speakers is better.

Thank you both for your input. I’ve decided to keep the Klipsch for now to play my vinyl and the Sonos equipment for TV programming. 
Now I need to figure out how best to set up and toggle between the two systems which shouldn’t be difficult. 

I think once you have everything and plug it together it’ll be straight forward enough.

Physically everything will be in the same room.

In the Sonos app you will have two logical rooms. One for the soundbar and one for the amp.

Being able to group the amp and soundbar, means you can play vinyl to both and experiment with turning the volume of just the amp off, so the vinyl plays through the sound bar. Makes it much easier to decide if you can getaway without the Klipsh.

I like the concept of soundbars and when I replaced my old 7.1 system looked at quite a few to see whether I could move to one for gaming, music and movies. In the end I ran with a split HT-A9 system for gaming, movies and concerts with a port + power amp and speakers for music, so didn’t really reduce my speaker count 

After about a year of running a dual system, I started building up my current setup which is back to an AVR with 5.2.2 speakers. So one more speaker than I started with when wanting to replace the 7.1 setup  but a different layout.