SQL Master Data Services database has huge leaf member staging table - can I purge old records?

One of our SQL instances has a large MDS database, and virtually 100% of the size is due to a 300+ million row table named stg.Stg_Project_Leaf. It recently started blowing up our weekly index rebuilds, so I need to figure this out. From what I can tell, this is a [Leaf Member Staging Table](https://technet.microsoft.com/en-us/library/ee633854(v=sql.110).aspx) for a "Project" entity, set up and automated (by a prior consultant) as a part of an ETL process that builds BI cubes/reports. Looks like it has been processing about 10k rows per half hour for the past *several years* and has never been purged. When I check the ImportStatus_ID, though, I see 0 rows waiting to be processed. (Most are 1 - succeeded, less than 1% are 2 - failed.) **Can I just TRUNCATE this table?** This system is being used in an automated fashion, its not like people are logging into the MDS console and individually monitoring and rolling back changes. I found some references to stored procedures that purge these tables (mdm.udpStagingClear or maybe mdm.udpDeletedMembersPurge), but I'm not sure which of those is the one I'd need, nor do I know if they would blow up the log if they tried to do 300m rows at once.