I have used EN 20 only one week before asking for a X9 license because this new version is really a disaster, as you say. And like you, I am an EndNote user for a long time.
It's the first time I see such an awful version of a software.
Thursday - last edited Thursday
First time I used EndNote 20 today (for 1h before I went back to X9). This is not an update, this is a jump back. All workflows are disrupted, useful icons disappeared. Whoever was leading the development team should be sacked.
My team will use X9 and we will skip 20 and all updates/new versions until the usability of X9 is fully restored.