great post. i'm the guy who's always, "dude, you'll never make it" ... but mostly because there's some time limit or ridiculous speed goal. at my first organized century, they were tearing down all the concessions when i got to the finish.
so yes. planning to go out at a reasonable, easy to moderate pace is key 'specially if 50 miles is what you've put in. the sense of accomplishment at the end is worth it.