The thread has moved on, with no further comment on Upnote?
I still have it installed. I still use it. Occasionally.
I decided to move it into test mode.
The issue with database PKM apps is that, in the absence of clear boundaries, they need to be all or nothing. The few file based apps (Obsidian, Tangent, Logseq to an extent) can all work on the same data and have full access to all the installed file utilities, but the database apps have to live entirely on their own features - possibly helped by any integrations they have with other programs - but they need all the notes or else the tags and links are degraded in value. Switching in or out of them can be easy or hard (Upnote seems easy for both), but there's a high cost to using more than one at a time. The links, backlinks and tags exist only within the database until they are exported. My small attempt to mitigate this is using only wikilinks and #tags, which means that I only have to move the texts around and don't need to rely on import/export algorithms, but it's still high cost to try to work with the same note collections in more than one program.
Which means it is a significant commitment to trial them seriously. Good import and export helps.
There's always the image problem in going from markdown - because it relies on links, you have to ensure all links are working. I've not tested this in any depth; I don't like using images in markdown notes because it's my experience that links will always break in the end. Would be better if the textbundle format were more widely used. But I don't think images export well to markdown. And imports probably work better if the images are in an external image library.
Tags import and export perfectly.
As does the text in the notes. Links work when imported, but can break on export because of syntax issues etc.
But mostly manageable. It's not as all in as with many.
I've seen many users put off by the low price. How can they keep that going? Only a small company (two developers in Vietnam). True; they do mitigate costs by limiting the size of notes and uploads, and say the database is optimised for 5,000 notes - which isn't that many really. But Evernote was big; Nimbus Note (which I mentioned originally in the same post as Upnote) has mutated to FuseBase and collaboration; Walling is now mostly about teams too; OneNote has been constantly threatened with being downgraded. I wouldn't be put off by that.
Others rattle on about the lack of E2EE. For me that's a manufactured issue. Few apps have that. There's encryption at rest and in transit. The old reset password trick will work if a hacker has access to your emails. I have no intention of storing my banking details in the app, but I'm not that worried about my notes.
And I have been concerned that I don't have a worked out Plan B for Tangent; I don't regard Obsidian as a viable alternative. And the concern has increased by its going open source. It may stay on the same path; but may also have alien bits injected which I might not find so comfortable.
And the Upnote design is nice and easy to work with. Like Heptabase it's essentially local with sync (Firebase in this case). #tags. [[wikilinks]], backlinks; no graph, although I doubt many actually use the graphs anyway. Easy, good looking info panel. Aimed at individuals not teams or collaboration; I assume that will come, though I'd rather the developers effort weren't spent on adding it. No AI as yet (I anticipate that it will come some time but at extra cost]]. I have it set for daily backups to markdown; and will do regular markdown exports into Tangent workspaces (the exports preserve file names (syntax allowing) - backups don't. No need to fuss over images. Good focus mode; ability to have notes in separate always-on-top windows. Good control of line length, line and paragraph spacing, although no first line indent; Enter=New Paragraph; typewriter mode. Custom option for the order in note lists which is something Obsidian and Tangent struggle with. Search is quite simple, but it does have replace. Colour text and highlight; I can't tell whether the underlying design is rich text sticking to markdown limits except with colour (I've read a claim that it is) but it can paste markdown and rich text and accepts writing in markdown formatting syntax. And in my relatively limited use so far it has been reliable and quite fast. It's not block based, which some will see as a disadvantage, and sections can't be dragged around, but that's no different to Tangent or Obsidian.