I'm in favor to make discovery the default also for JSPUI. I haven't tried this patch myself but it looks like only the "search" provider is changed to Discovery/SOLR, there are some changes to the BrowseArtifact too but it looks like source cleanup / refactoring.
Let me know if you like to have a separate pull request for change the default search provider also for the JSPUI and eventually also change the default provider for the browse system. Please note that as the BrowseDAO are implemented as DSpace plugin we can only change the configuration for both UIs.