@PATRICKOBRIEN1 We have a similar setup in my district (PowerSchool through our state and ClassLink for rostering) -- because our state sets up our SIS integrations with Canvas, I had to integrate with the SIS directly instead of rostering through ClassLink. To give a sense of how large my district is, we have close to 170,000 users of Canvas.
With rostering with the SIS (OneRoster):
Ease of Use -- it's automated. We have roster updates every night from the SIS.
Notifications of success/failure -- unfortunately, I don't think the integration supports email notifications, but I do spot check and it will let me know if it's failed or not. (I usually get support tickets letting me know if there's a problem, so I usually use that as my canary.) You can also re-run a scheduled roster send if it did fail (for example, if the SIS went offline).
Timely integration -- could you explain what you mean by 'timely integration'?
To add to this, with rostering with the SIS we do get grade passback, which means that teachers can send scores from Canvas to PowerSchool (one way sync) so it's a really great way of saving some time with grading.
Some considerations:
You can roster with the SIS and have Classlink as your SSO. We have this setup, it's just a matter of making sure that the "login" field of a user is the same login as ClassLink. (We also have 2 more SSO methods, Google and our state SSO). It works extremely well for us and it's a good backup just in case one of the SSO methods goes down (which can happen!)
Hope this helps!