Quicksearch box in navigation menu doesn't always return all results

By the way the demo user on sandbox seems to be locked out, but this can be reproduced on drupal.demo.civicrm.org.
In there are 9 contacts with last name Adams.
In the quicksearch box type "a". It returns a bunch of random stuff, and I know there's a built-in limit of 10. That's ok.
But now, since the autocomplete cache has only been filled with 10 items, when you type "d" it only returns the subset of results from those 10 items, none of which are Adams, and in fact it isn't until you type the fourth letter "m" that you get any of the Adams.

I did some local testing and adding "matchSubset: false" in templates\CRM\common\navigation.tpl to the autocomplete seems to solve it. It DOES increase the number of hits on the server, but only the first time you use a given sequence. Well, up to a maximum of 10 sequences which is the default of cacheLength, and then it starts hitting the server again if you repeat a sequence from before your last 10, but the cache seems to reset on each page load anyway so it's limited as to how much the cache helps in the first place regardless of whether cache is used at all.

What do you think?