I've never run a marathon, so I can't compare from my own experience. Given that comparing cycling to running is an apples-oranges comparison, there are still some parallels. I think a century roughly corresponds to a marathon. In my experience, the "wall" effect hits around mile 65 or 70. If you're in decent shape, have decent endurance, and have done some distance so your body is used to using fat as fuel, you don't experience it.
Other runners will probably disagree, and I'm not much of a runner any more in any case, but I always felt like 7 miles on the bike corresponded to 1 mile running. (disclaimer: at *my* running and cycling speeds). Or, an equivalent workout on the bike takes about twice as long. That in no way agrees with Dr. Burke's article. That's based mainly on perceived exertion and how I feel after, say a 1/2 hour, 3.5 mile run vs. 1 hour, 20 mile ride.