Made the switch after Zscaler's last price hike. Ran both in parallel for a month, then full cutover. Six months in, here's the raw data.
**Cost:**
* Reduced our total secure access spend by ~35%.
* Biggest saving was in the user-based licensing. FortiSASE's bundle is simpler.
* No more surprise add-on fees for the CASB-like features we actually use.
**Performance:**
* Latency is comparable for our primary regions. Zscaler had a slight edge in APAC, but not enough to justify cost.
* Tunnel stability is better. Fewer random drops requiring agent restarts.
* DNS filtering and SSL inspection work as advertised. No major functional gaps for our needs.
**Operational:**
* Terraform provider exists, but it's barebones. Had to write more custom scripts vs. Zscaler's mature API.
* Integration with our existing FortiGate firewalls was straightforward. Single pane of glass is real.
* Alerting and logging took more tuning to get right.
Verdict: For a shop already in the Fortinet ecosystem, it's a no-brainer for cost. If you need deep, granular API control for everything, evaluate carefully. It does the core job well for less money.