Considering that a storm jib can be used as the only sail under some conditions it would seem unlikely that a designer would draw something that fails just when itís most needed. Under all the conditions that I can think of just now, before my second cup of coffee that is, a main is trying to push or pull the panels of a mast out of column and that is harder on a mast then just the compression from a headsail. This assumes that the headstay pull is balanced by a jumper, running backstays or upper termination point of the upper shroud at the headstay with swept spreaders. If a particular boat is poorly designed then itís just poorly designed but offhand I canít think of a boat where I would be concerned as long as I used the running backstay, if rigged for one, and had the rig tuned properly.
All the best,