I just recently started working with this module. I stayed away until now, hoping Views would catch up. But... well... 'nuff said.

I'd like to see the query building options and logic refactored into a context plugin. I've actually started doing this, but it entails refactoring quite a bit of the content_type plugins. $search would become a Solr_Base_Query object, built in the context. The type rendering function, which builds this variable, would instead get it from the context. Perhaps the options on the content pane could remain as overrides.

And again, since the query is built in the context, the search would be executed not in the theme function but either in a solr response context (relationship from query context) or in the render function. Again, much refactoring.

Don't want to put too much in this issue. But these are my ideas. If they seem good, I'd like to submit some patches.