The main downside is that if you rename a widget after a Px Property is already linked by it, it can break your Px page. That is caused by the Px Property now targeting a slot name that does not exist.

To avoid this, you must manually unlink and re-link any linked properties after renaming a widget, or you may need to edit the XML to repair your Px page by hand.

As a general rule, Px pages should always be edited with Preserve Identities set to the same value with which they were created. Saving a Px page with a different Preserve Identities setting can lead to the problems described above. Since its default value is false, you should work with Preserve Identities disabled unless you have a specific need for it. The Preserve Identities option is also available when using the Px Media Migrator Tool or the browser's Media Settings Tool. For more information, see the “UxMedia” section in Workbench Help. The same advice applies.