You should be able to check your logs for instances of the "soft 404" and 404 Not Found errors - see what's happening by spot checking a bunch of them randomly over the period in question.
Reducing the MySQL search string limit might have had the undesirable consequence of causing db related content serving errors, although you'd expect to see more error 500's showing up then (check logs).
I've not noticed any issues getting content from the site over the past six weeks or so.
PS: Searching for rx1 and RX1 fails to return any result.