How can I professionally evaluate or challenge a Dynatrace rollout when we already use Application Insights?

Both tools can run at the same time, and some teams do this successfully. The important questions are whether the additional coverage is worth the licensing cost, whether telemetry will be duplicated, and who will own configuration, alerting, and support. Ask for a documented comparison and a limited pilot before making a final decision.

Before deploying anything widely, ask for an onboarding and operating plan. It should explain which signals each product collects, how duplicate data will be avoided, what alerts will be authoritative, expected application overhead, and how costs will be controlled. If the answers are unclear, recommend a staged trial rather than blocking the project or interfering with it.

If you oppose the rollout, make a clear business and technical case instead of trying to sabotage it. Compare capabilities, data retention, pricing, agent overhead, privacy implications, integration with existing systems, and the effort required to operate each platform. A proof of concept with agreed success criteria would make the discussion much more objective.

Dynatrace is generally a broader observability platform, while Application Insights may be sufficient for application-focused monitoring. The right choice depends on what your organization actually needs. Consider instrumenting applications with OpenTelemetry so the telemetry is less tightly coupled to one vendor and can be routed to an appropriate backend.