Can you use dual-WAN with Active/Passive failover on any of the TZ SonicWALL models?
The TZ series can be used for a dual wan connection.
WAN Failover and Load Balancing allows you to designate the one of the user-assigned interfaces as a Secondary or backup WAN port. The secondary WAN port can be used in a simple active/passive setup, where traffic is only routed through the secondary WAN port if the primary WAN port is down and/or unavailable.
For Active/Passive, as described by the article, it is possible to do so.
Edit: on the right section, you see on what appliance it is available (Which includes the TZ series)
Hope this helps.