@Blob_Eater: We left it at that moment because the issue was in our production system. We wanted to make controlled changes and monitor what the result was. There have been several discussions since this issue about parallel plans and finding other big offenders.
@alan.B: Thank you very much
@Iwas Bornready: Agreed. In this case, the query was ripe for an index so it made more sense to add that instead of defining a MAXDOP on the query.
@Claudiu Balciza: We actually have the PK on another column that is based on the survey response, not survey ID.