Before we get too far into the argument, the answer seems to be: maybe? It depends? At the very least, you wouldn’t necessarily think so, but the enterprising folks over at Team O’Neil Rally School decided to give it the old college try and see if there is a difference.
If you watch the above video, you’ll see that there does indeed seem to be a noticeable difference between having 4WD engaged. They also disabled the ABS in their Ford F250 to see how much that affected things as well.
Now, it must be said that their test wasn’t exactly scientific. They admit that they aren’t sure exactly how fast they were going, so that calls the results into question, but for now, I guess the answer is “might as well use 4WD to brake.” For those interested, Team O’Neil undertook another, slightly-more-scientific test, this time using a couple of Jeep Cherokees. Check out that video below.