When planning a VPN deployment, for which reason does an engineer opt for an active/active FlexVPN configuration as opposed to DMVPN?

Both DMVPN and FlexVPN can be configured with multiple routers or VRFs, so this is not a distinguishing reason to choose FlexVPN over DMVPN.

In an active/active FlexVPN setup with multiple tunnels, traffic distribution is typically managed through routing or policy where it can be statically distributed across the available paths. DMVPN, especially Phase 2 and 3, is optimized for dynamic spoke-to-spoke tunnels and generally relies on routing protocols to determine paths rather than static distribution across multiple active tunnels to the same hub.

Floating static routes are a general routing mechanism for backup paths and are not exclusive to or a primary differentiator for choosing active/active FlexVPN over DMVPN.

HSRP (Hot Standby Router Protocol) is a First Hop Redundancy Protocol (FHRP) used for local gateway redundancy and is not directly related to the core VPN architecture decision between FlexVPN and DMVPN for active/active scenarios.