1. Search:
a) Search function now seems limited to "Collections" and does not include "History" sessions at all. Major deal breaker for me, at least. Most sessions I have were auto-created by the close of the browser - be that manually closing the browser, or an unexpected close.
Why are History sessions not included in Search? Checked "Settings". Doesn't seem to be an option to change that.
b) Search results used to display in the main Chrome window, with matching Sessions at the left. Now it seems to just be a drop down from the Search box instead. The former was much more robust and useful. The latter is... lacking.
2. Manipulation of Sessions:
Prior to the v4 upgrade, there was no real distinction between "History" and "Collection" sessions. This meant that multiple sessions of either type could be manipulated using Combine/Merge/Save/Copy/etc.
Multiple "History" sessions can no longer be manipulated in this manner.
3. Backup/Export:
Prior to the v4 upgrade, the "Backup" option (which seems to have been removed) exported ALL sessions, including the aforementioned History sessions. There does not appear to be an analog to this functionality under v4.
Prior to the v4 upgrade, the Export feature also allowed saves in multiple formats for all sessions at once, using text, CSV, Markdown, and HTML, in addition to JSON. (though a separate Export operation was required for each format type).
In v4, Individual History sessions can be exported in those formats, but again, only on an individual History session basis. There seems to be no way to select more than a single History session at once.
In v4, are History sessions being backed up and/or exported? It is difficult to tell.