brew upgrade --fetch-only versus --quiet for low-noise update alerts

I need a periodic Homebrew check that alerts me only when a formula has a new version that can be upgraded without hidden dependency problems, while keeping terminal output and log noise to a minimum.

Two documented approaches are available: brew upgrade --fetch-only stages the download without installing, letting brew outdated show upgradable formulae, and brew upgrade --quiet performs the upgrade but suppresses progress bars and standard output, relying on exit codes and error messages for alerts.

I am unsure which approach better balances low noise with visibility of critical warnings that could block a successful upgrade.

• Does --fetch-only combined with brew outdated reliably surface dependency conflicts that would appear during an actual upgrade?
• Can --quiet be trusted to expose important warnings through its exit code or error output, or does it risk hiding them?
• Which method yields fewer false‑positive alerts while still notifying me when an upgrade is actionable?