In general I'm not a fan of critical fumbles for many of the reasons that Ghostwheel mentioned. It seems like most critical hits and fumbles end up either being "oops, lose your next turn", "oops, lose some resource that might be a pain to replace (like your weapon)", or "oops, receive some injury that's outside of the scope of the HP system, which we'll have to figure out a way to fix when we get to the next town".<br/><br/>Any of the three of these effectively serve to take a player out of the action for some length of time, even if it's only a single combat round, and that's particularly bad on forum play where that could result in a week of player downtime. If the tables include drastic things like "lose a leg" then you could be even more screwed.<br/><br/>I count critical hit tables and critical fumble tables as pretty much the same thing here, since most of them tend to echo each other. Either it's "you lose your grip on your sword and it goes flying" or "you hit the guy really solidly and make him drop his weapon". Same difference.<br/><br/>The standard critical hit confirmation system, though, is pretty... ahem... critical to Pathfinder. There are lots of feats and special abilities that rely on that system being in place. It also gives you different flavors of weapons. Without the critical system the rapier is just an inferior longsword that inexplicably costs more money. With the critical system it's a longsword with a higher chance of slipping in and doing a more deadly wound, though on regular blows it's less effective. I like that degree of specialization in the system.