Participant Status vs. Participant Status ID
I don't think anything has changed.  Every participant status has both a label/name as well as an assigned ID (integer) value.  The search builder lets you construct a search using either construct.

I do see on the 4.6 sandbox, that when I select to search on Participant Status ID that its possible option values are the names rather than the ID's.... however the result set still came back correctly and displayed the ID's.

I suspect this behaviour goes back to v3 days.