There is something to be said for not risking your mainsail in a blow. The problem is, that without a sail aft of the mast you aren't going to be able to go to weather. The wind will just blow the bow off and you'll be forced to sail down wind. Hopefully there isn't any hard water in the direction you'll be forced to go.

A cruising main should be stoutly built out of heavy cloth, strongly reinforced and well stitched. In short, it should be able to take a beating. When you reef, you reduce the stress on the sail so, up to a point, its no different than sailing with a first or second reef. You will reach a point that you risk destroying the sail but, at that point, you'll probably be in a survival mode and have handed the sail in any case. Most boats will go to weather in 40k winds. Once you get much above that, the wind and sea state force you to run off before the weather under bare poles dragging a drogue or some means to slow you down. Yes, I'd rather have a storm tri sail but I can't rig one on my boat because of the mast shape. A 3rd reef is the only way to have the ability to go to weather in Gale Force conditions.

For those who advocate that two deep reefs are the way to go for a cruiser, I say no way. I want the right amount of sail up for the given conditions. Don't want to be constantly playing with the sail, but in a cruising boat you may have the same combination up for days or even weeks at a time. My recent Transpac, I ran wing and wing with a full main and the 135 poled out for almost two weeks and only jibed once. Occasionally put the typical sized first reef in when a squall passed. If the winds had been stronger, wouldn't have wanted to cripple the speed because of too deep first reef.