You have always been very well informed and helpful Pink Elephant, I thought I should say this.
On the points that you mention another member has already answered to you above. I have also made the step away from EN (although my subscription is still active till end of the year) and towards Devonthink Pro.
I verify that the backup can be done in iCloud for DT also.
Learning curve is indeed steeper than EN, becoming a "pro" user will for sure require more time in DT.
Regarding price, given the new pricing of EN and the fact that it takes 6-7 years for DT to change version, the later is definitely cheaper in the long term.
Main issues that made me change:
1. Speed. I had noticed that EN was starting to lagging to the point I was getting annoyed, especially in iOS (even in brand new devices)
2. Privacy. I wouldn't trust EN (or any such cloud service) to store valuable documents (IDs, Passports, Health documents, financial statements). With DT everything is encrypted in my device, easy to find but also safe
3. Locked in. I know that many will say that you can take your data, but in reality this is not the case anymore with Evernote. Exporting in pdfs is just NOT an option and bulk export was made impossible with v.10 (I know read they bring it back). In any case, trusting them with thousands of notes only to lose them some day if they go down it's just not an option for me. With DT i can just drag and drop a note somewhere and voila!
4. Lack of markdown
Reasons 1,2,3 are the ones I also left Notion after trying it for almost a year.
Problems of DT:
1. Search function, although powerful in DT gives less often what I am looking for as the first choice. I usually have to go down the list of the results to see what I was searching for. In EN, with some magical way it was always one of the first 2 or 3 results, even if i had mistyped something!
2. The mobile version of EN rocks while in DT it (almost) sucks. It's fast alright, but there stop the advantages of it
and also,
3. Difficulty sharing notes with others. If this is a priority for you, then clearly DT is not an option
4. Doesn't work with anything other than MacOS, iOS, PadOS.
The last two are not issues for me but maybe for some others.
Last but not least: the support team of DT just rocks!!! It's really incredible, like these people are 24/7 in the forum answering issues/problems. They listen to the customers and plan implementing new features. Also others users are really active and responsive to any questions you may have. I have honestly been impressed, only among Linux users I have seen such devotion to a product in the past.