Work across two Macs
Your ratings, keywords and collections follow you from one Mac to the other. Your originals never leave their drives.
Online: Catalog Sync through Dropbox
Connect Dropbox on both Macs and Mantle keeps their catalogs in step, previews included. You can see what's syncing and settle anything both Macs changed.
Offline: carry it on a travel drive
Choose File › Travel Drive Sync and save to the drive. On the other Mac, choose Merge into this computer. Before you merge, Mantle shows which Mac saved it, when, and how much it holds. Before you head back, do the same in the other direction.