Non-destructive faceted browsing

There are two methods of browsing faceted search results.

The first - as produced by Solr, eg VuFind - is destructive: when you select an item from a facet, the other items from that facet become unavailable and you have to go back to recover them.

The second - as produced by Exhibit, eg Haystack Publications - is non-destructive: when you select an item from a facet it's highlighted, but the other items remain and you can include multiple items from the same facet in the query.

I think I prefer the second method, although it can lead to items remaining in the list that have 0 results.