I wouldn’t think so, no. Slight, perhaps, but not marked….but then, you should do your own comparison, my ears are not the same as yours. Go to a local retailer who has both on display, and determine for yourself. 

I have both One’s and Era 100’s paired - there is an improvement, not least because the Era has two tweeters (they provided stereo output when standalone), but it’s perhaps not a huge upgrade unless you need Bluetooth and line-in audio options. If not, I would only do this if there was a plan to use the Ones elsewhere in the Home too. 

What is worth considering though, is to swap the Ones for Era 300s - that’s a huge “night & day” difference in sound, particularly with Atmos audio. The 300s are one of my favourite Sonos products and I highly recommend those speakers to family & friends. Of course they have Bluetooth and line-in options too. Either way, these would be my choice if I was looking to upgrade. 

I will just mention one further thing, just in case… the Sonos One speakers do support the Google Home Voice Assistant, but that voice service is no longer available on the Era products, which now support only Amazon Alexa and Sonos Voice Control.

Thank you Ken and Bruce for your advice.

As you said Ken I really need to hear the era 100’s for myself either in store or preferably a home demo.

The era 300’s although very appealing would not work for me due to size and placement.

I have an Arc ,Sub and two play 1’s in my lounge of which I am more than happy with but I do understand how the era 300’s could give me more.

Thanks again Jason.