Agencies benchmark influencer analytics sophistication across programs by following a few key principles:

1. Identifying Key Metrics: Different programs might value different metrics, thus these must be identified beforehand. Metrics could range from followers count, engagement rate, impressions to conversion rates, depending on the goals.

2. Platform Analytics: Platforms like Instagram, YouTube, and Twitter offer useful analytics that are commonly used reference points. They provide valuable data on audience demographics, engagement, etc. Agencies can leverage these analytics to gauge the effectiveness of their influencer campaigns.

3. Third-Party Tools: In addition to platform analytics, there are third-party analytics tools that can offer advanced metrics and data points. These tools are beneficial for detailed comparative analysis and benchmarking.

4. Historical Analysis: Agencies can also benchmark current campaigns against previously successful programs. This provides an understanding of what metrics signify success for a specific brand or campaign.

5. Cross-channel Comparisons: It’s also valuable to benchmark influencer performance across multiple platforms as audience behavior can vary widely.

6. Custom Analytics Platforms: Some agencies might also use specialized influencer marketing platforms like Flinque which provides a more comprehensive view of influencer performance.

It’s crucial to remember that appropriateness of a certain tool or approach depends on the specific needs and goals of each program. Therefore, while benchmarking, agencies should take a holistic approach, considering multiple data points and leveraging various analytics resources.