A practical limit on ACE module is 4k each for probes, serverfarms, class-maps & policy-maps. Rserver instances can be up to 16K. These limits represent total per system. They may exist all in a single context if desired. These numbers will vary based on specific configuration requirements.
For more specific guidance please reach out to your account team or technical marketing engineer.
Other resource info can be found under Cisco Application Control Engine (ACE) Troubleshooting Guide -> ACE Module Resource Limits: