Considering that the forces involved in holding the wing halves together are very small, the rubber band will work with no problems. The only time there will be any considerable forces pulling the wing outward should be during a fast roll, still no concerns with the stock setup. As a matter of fact, I have heard stories (both good and bad) that the plane was flown without anything holding them together because the pilots forgot to put it on. However, I use a rubber band and a zip-tie just for redundency. Use what you feel confident with, but I see no reason for any big modifications. Like they say, If it aint broke, don't fix it!