This could replace SOLR for one of my sites - I'll need to do some benchmarks to compare them when deciding if it makes sense to move. If so, I can probably post CloudSearch:SOLR comparisons at least.
it seems that the latest Solr 3.5.0. release use less memory: Bug fixes and improvements from Apache Lucene 3.5.0, including a very substantial (3-5X) RAM reduction required to hold the terms index on opening an IndexReaderhttp://lucene.apache.org/solr/solrnews.html