I just went from old Avast to Avast One. The learning curve does not seem bad at all. The main difference I notice so far is fewer settings options in Avast One. But so far that has not been an issue. I previously used Premium Security for one device. The reasons I went to Avast one were two: I was having an issue with the subscription on Security. And two, I had finally decided to use Avast on my two Android devices. I just decided to go to the Avast One version that allows up to 5 devices. There are also a couple of additional features included in this version that I don't think are in the free version, although those do not seem all that important.
It has only been two days so far, but I have not encountered anything that would make me think I should not have changed to Avast One. On the other hand, I have not encountered anything that would make me think changing to Avast One has any great advantage. In my case it was just a choice between trying to get my Internet Security subscription issues resolved and then upgrading that subscription to include multiple devices, or going to a 5 device Avast One subscription. I just decided on the latter.