In the #solr IRC channel, I mentioned the maxBooleanClauses limitation to someone asking a question about queries. Mark Miller told me that maxBooleanClauses no longer applies, that the limitation was removed from Lucene sometime in the 3.x series. The config still shows up in the example even in the just-released 4.2.
Checking through the source code, I found that the config option is parsed and the value stored in objects, but does not actually seem to be used by anything. I removed every trace of it that I could find, and all tests still pass.