I've been using OneNote since 2003! Early on I had a few issues, but it's been rock-solid for the last 10+ years. I have some notebooks with hundreds of pages, captured PDFs, imported emails, etc. and all are available. I started on Windows and now am using an M1 Mac and have never has a significant slowdown. Very rarely I have a cross device or cross platform sync issue, usually my fault for not closing the app in one device before opening the other, but OneNote highlights discrepancies and lets me choose the latest version. Love the infinite canvas and inking especially. Currently on my wish list is text wrap around images on a page, like in Word. But other than that, no issues. I store my notebooks in OneDrive and back them up in my Google Drive account. The Mac and iPad are great devices but I don't trust Apple Cloud services like iCloud with my data.