This is still feeling very subjective, however that’s what we’re left with given few hard statistics. See usage of roughly two million backups per month. You can scan the forum and issues for problems (and determine if it looks less reliable than you accept for your production), and the releases to get ideas of where changes go.
Duplicati should grow more reliable and have fewer rough edges as it matures (at some point the Beta label should disappear), but it’s useful to lots of people, and is far better than no backup (and two is even better).
Rough edges are easier to have opinions on, but as just a user I can only guess at futures from posts here.
From your list, scheduled backups can be done either at user login (default), or as a service (rough edges).
A “real problem” is subjective, but no on-screen alerts will happen until when/if a Warning or Error happens, which causes a popup on the Duplicati page in the browser (and changes color of tray icon if you have one). Rough edges then include having to figure out which of several logs details the issue, then make sense of it. Recovery is sometimes easy, sometimes less so. Tools are imperfect. There seems some planned work here.
Alerts by email, http (maybe to a monitoring service), etc. are quite configurable. Rough edge is consistency.
Slow uplink is easy because only changes are uploaded unless a compact is permitted (it grows busier then).
Total drive failure should not be a problem, but depending on the backup size (including versions kept) might interact with Internet and other speeds to make it slower than you’d prefer to get everything running normally. Restore is usually a point-in-time view, so “last weeks data” may include the files that have been there awhile. Old files might be more subject to undetected destination damage. BTW scp is not out yet, but you could ask. –backup-test-samples or The TEST command can be used to test health without actually doing a big restore.
If you’re not on a metered connection, maybe you can do your own testing to simulate the recovery you seek.