To investigate what kind of snippets are better suited for structured search on mobile devices, we built an experimental mobile search application and conducted a task-oriented interactive user study with 36 participants. Four different versions of a search engine result page (SERP) were compared by varying the snippet type (query-biased vs. nonredundant) and the snippet length (two vs. four lines per result). We adopted a within-subjects experiment design and made each participant do four realistic search tasks using different versions of the application. During the study sessions, we collected search logs, "think-aloud" comments, and post-task surveys. Each session was finalized with an interview. We found that with non-redundant snippets the participants were able to complete the tasks faster and find more relevant results. Most participants preferred non-redundant snippets and wanted to see more information about each result on the SERP for any snippet type. Yet, the participants felt that the version with query-biased snippets was easier to use. We conclude with a set of practical design recommendations.