What It Deduplicates:

• People
• Companies
• Deals

What It Moves Over During Merge:

• Activities/Notes
• Events and Tasks
• Fields and Custom Fields
• Associations to People, Companies, and Deals
• Files/Documents for People and Deals

Where It's Limited:

Documents for non-master Companies don't get moved over on merge.

Revenue Type field doesn't get populated during Deal merges.