http://www.thehighroad.org/showthread.php?t=170763
(...including this: "Without a single exception, functional problems with the FAL were, in [the Israeli military contact's] opinion, the result of either substandard or non-existent maintenance on the part of Israeli personnel. In other words, the gun worked fine as long as routine maintenance was performed.....")
(Sounds just a bit like the M-16, doesn't it? ;>)
For a more applicable (and better documented) reference, just check out "Ol' Dirty - A Texas Legend:"
http://www.falfiles.com/forums/showthread.php?threadid=68486&perpage=30&pagenumber=1
As per a recent update, "Ol' Dirty" (a home-built West German G-1 FAL) had 10,000 rounds (plus 'swamp tosses' ;>) under it's belt - without cleaning - and was still running strong. Try that with your favorite AR...
(Speaking of which - suggesting that the Israelis replaced the FAL with the M-16 due to undocumented reliability problems would be akin to suggesting that the US replaced the M-14 with the M-16 because the M-14 was unreliable... ;>)