Artificer, can you take a Medium instead Large size Mechanical Servant?

@MerlanMichael @JeremyECrawfordIn the new UA Artificer it states select a “Large” beast for Mechanical Servant, can you take a Medium instead? yes, Large size should be limit rather than only option #wotcstaff

— (((Mike Mearls))) (@mikemearls) January 14, 2017