I've never actually played Call of Cthulhu, but I've read accounts of games where there was almost a revolving door of characters coming in one session, getting devoured or going nuts the next session, and a replacement character coming in the third. I've always found this baffling — how can you get any emotional investment in a character who's only going to be around for six hours or less of gameplay? And how can you come up with concept after concept when they get knocked down like so many bowling pins, short of resorting to "This is Agatha Lovejoy's twin brother Arnold Lovejoy..." followed by "This is Agatha and Arnold's cousin, Rupert Lovejoy..."
On the other hand, if the characters aren't threatened by combat, the natural instinct of most gamers will be to shoot first and ask questions later (if at all). Nothing takes care of gibbering cultists quite so efficiently as a Thompson equipped with a 50-round drum — at which point you're playing Doom or something instead.
So, it's a paradox which is going to require some thought. I'm curious, any of you out there in LJ-land who have played CoC (in any incarnation), how deadly was it? And how did it impact your experience? I'm very interested to hear about it.