A DirecTV user as of early May, 2014: I switched to DirecTV from Dish because my DVR was fading and Dish wanted to charge a lot to replace it -- and I could not move my recordings and searches to the new device; I thought I would check out DirecTV.
Once the DirecTV Genie was up and running, I loaded the 'Recent Searches' with the shows and movies I had lost in the transition and have since found the Search useful, not only in recovering some of the things I had to abandon, but also for later discovered rare items.
Recently, I noticed some things had disappeared from the list, but it seemed to be an uncommon event so I wrote it off to user error. However, just 'yesterday' (~2+ months after their input), most of the list was gone, both items for events I had not yet recovered from my Dish days and events I routinely 'find' and record.
(IF THEY STAY ON THE LIST, it is easier to use the search to find and record occasional events than from a guide list, however that is configured; eg, daily shows that I only want to record once a week (but which I view less often).)
I realize 'Recent' suggests things might not stick around on the list, but some of us, dph2902 & I for instance, do like to keep an eye out for rare shows/movies rather than merely to see what's on NOW -- If Recent Searches will not persist, is there another way for us to keep a watch without periodically reentering things?