There is no argument that a .22 can be lethal but it is not a good stopper. Trooper Coates was killed by a .22 but he did not die immediately and continued to present a threat to the fat slob that shot him (though unfortunately not a lethal one).
Most bullets are pretty effective in the brain box. The trick is getting the bullet in there.
As was said above. It is better than nothing and I don't want to be shot with one.
I don't think it would be wise to depend on just a .22 to protect yourself but I like soupbone's point about a GSW being far more serious in an emergency, SHTF, EOTW situation.
I haven't thought it through completely but it seems like having a .22 to burn a few rounds at people who need to be somewhere else and a more substantial gun to actually stop them might be an effective system. Having written that I generally think folks should refrain from shooting unless they actually mean it.
If you'll permit me to develop the idea as I write I think you could set it up where you shoot people (who need to be shot) first with the .22 and then if they are not discouraged follow it up with heavier rounds.
All that is with the idea of defending an area.
You wrote about "rapid .22 fire" though. For a .22 to have a reliably meaningful impact on a target it will need to be more accurate than fast and even if you can shoot with 0.1 second splits you're still just shooting small lead pellets.
However, there is absolutely no reason not to stock up on .22 ammo. Even if you don't own a .22 it would be good for barter.
A note on the 25 round 10/22 mags. Have you shot them with the ammo you plan on storing? They are famously unreliable. If yours work then great. Just be sure. I've heard that Ruger has just introduced their own full capacity banana mags that are supposed to feed well.
http://www.ruger.com/news/2011-04-29b.html
I have no experience with it though so YMMV.
Ben
Interesting discusssion. MY TI 25's composites and BX 25's are working flawlessly. A couple days ago I shot 600 rounds through my let's test the 10/22 barrel (just a regular extra 16 inch factory ruger barrel I have) non stop. I shoot CCI blazer which I've done immersion tests on and it has very good qualities. I've never had a dud. The gun kept firing till I was out of 600 rounds. I experienced no misfeeds, stove pipes etc. FLAWLESS. The gun was VERY hot (again just for testing) that I could feel heat through the magwell.
Was this test extreme? yes it was, but it shows how a 10/22 with BX-25 mags and or TI 25's can keep on ticking. An asset if the chips are down for sure.

Taken from what i've posted before on hoodswoods.
Thoughts on 22's.
1. Low report. Low muzzle flash compared to the other firearms. Lower gas volume. Easy to suppress. Easy to get subsonic ammo which is pretty quiet on it's own right. If I set up a hide in an urban room, the whole room wouldn't shake from the excessive muzzle flash and recoil of the .22's like some of the more powerful cartridges. On the ground, it's not going to stir up the a large amount of dust/ leaves like shooting a 308 will. Prepping your hide is still a good idea....
Israel used modified 10/22's at one point
http://www.ruger1022...aeli_sniper.htm The Russians fielded the Izhmash SV-99 a 22 rifle
http://www.pmulcahy....iper_rifles.htm
2. I trust most have seen the 300 yard turkey test with a .22 LR.
3. Easy to teach people to shoot 22's with it's light recoil.
4. If you have a mag fed bolt or semi reloading is easy and quick. The low recoil of 22's make delivering rapid fire easy. I would not want to to take 3 shots of rapidly delivered .22LR from a 10/22 to my windpipe/neck/head from 100 yards. Don't think the 22's can penetrate the skull at your given distance? The neck is such a fragile target, so many vital components to the human animal in there. Is it a quick kill like a CNS shot, no, but who wants to get hit in the spine/windpipe/carotid arteries??? Not I, says I
5. Quotes taken from 1993 Gun Digest, article The Quiet Rifle.
a. " The Lethal Range of the Long rifle cartridge is far beyond it's "effective" range- close to three-fourths of a mile on an adult human, hit in a vital area. Paper ballistics are rather misleading in this respect. While they show a significant declines in velocities and foot pounds of energy over a hundred yards, author tests with a 22 high velocity solid bullets, for penetration in solid plywoods, evidenced only a .2 inch decrease between 25 and one hundred fifty yards.
b. "The Remington Yellow Jacket, with it's large cavity, expands with explosive results which are enhanced by the cavity being filled with bullet lubricant, which behaves as a semi fluid. The effect on woodchucks is very lethal. Grackles and starlings are often pulped to a point of being blow in half; so are squirrels, which makes it a poor choice for pot hunting.
c. The short qualifies as the most quiet of useful hunting rounds, making a pop a little loader than a pellet rifle. It's small size and mild report belie it's deadliness. In solid plywood tests, the high velocity solid will go through 1.5 inches at 25 yards, as compared to the high velocity 22 LR at 2 inches at this distance. A penetration of capability of .5 inch of plywood is enough to cause death in a vital area hit on a person. Documented fatalities with the 22 short have occurred at 600 yards. The short does best in a barrel bored for it alone, but is remarkable accurate in some Long Rifle barrels.
http://www.hoodswoods.net/IVB/index.php?showtopic=38197&st=45&p=449926&hl=fatalities&fromsearch=1&#entry449926http://www.hoodswoods.net/IVB/index.php?showtopic=43701&hl=hide&st=15Peter's post as usual has reallygood points.