The output of Azaroth’s meeting with A9 is up on their blog. Sounds like it will be a meeting of the minds, halfway type of thing. Being extension’s it might make it possible to keep the great simplicity of OpenSearch while taking advantage of some of the more advanced queries that SRU allows. From the post:

We see many opportunities for collaboration going forward. To start, we hope to foster ongoing dialog between the OpenSearch and SRU communities. And on the technical side, there are several obvious ways in which the two formats can interoperate. For example, the OpenSearch Query Syntax could incorporate elements of CQL to perform more structured searches — a thorny challenge that benefits from reusing prior efforts. On the response side, OpenSearch queries can be used to fetch structured SRU result sets. We even discussed ways to use a simple XSLT to convert SRU explain records into OpenSearch Description documents and SRU result sets into OpenSearch Responses on the fly. This will be particularly useful in integrating SRU-enabled resources directly into the growing number of OpenSearch-aware clients.

Will be interesting to see where this leads. I was playing around with allowing CQL type queries in opensearch but this will make it much more standardized.