Hello,
 
I think your friend bought into the bigger is always better argument which isn't true all the time.  I think placement is more important.  My CCW instructor told us that 0.380 is the minimum caliber for self defense, yet the example he gave in class for self defense showed that even with 40-45 caliber bullets attacker was smaller than your friends 6' 200lb attacker are taking multiple hits and drove himself to the hospital.   The attacker's buddy who was also hit wasn't so lucky and died on the spot.  
 
 My experience is that hot 32 ACP ball ammo penetrates very well almost to the point of being able to punch through a man sized target, and is a serious caliber.  It's not a big bore, but it will get the job done at close range.  That's why I carry a P-32 most of the time.
 
Thanks:  

I carry my P32 more than maybe any other gun I own.  Reason why is that with a modified Uncle Mike's holster I can carry extra mag and gun in one pocket and a NAA mini in .22LR or .22WMR in the off hand pocket or on ankle and be extremely well concealed.  Not to mention I can run my non-gun belt loose one notch with that setup and still never have to tug them up.  Even when I have my PF9, j-frame or Glock 30 IWB the P32 or P3AT is up front right, although when carrying IWB I usually carry the P3AT in a nemesis with no extra mag front right pocket.  
 
I think the .32 is enough as I plan to shoot until the threat stops.  I feel that 8 of .32ACP is enough to stop one man and maybe two if I pay attention and do not mag dump out of pure panic.  However if I do, the extra mag will come in handy if I have enough presence of mind and time to reload.  If not or the P32 fails catastrophically, the mini revolver may be better than nothing.  
 
I feel comfortable with 10+ rounds in any configuration as long as the caliber of half the rounds is a decent caliber for stopping two-legged threats.  I hope I never, ever have to even pull my weapon out other than to put it in the safe at the end of the night, but if I do I mostly agree with the stats on average distance and number of shots fired in self-defense situations, so generally a 5-shot j-fame makes me feel comfortable enough.  However I like having an extra position covered to draw from and I like having a few more rounds for multiple assailants as I will most likely be protecting my spouse and child.  
 
So to the original question of is it enough?  For 1 assailant, probably.  Borrowing from Shanghai_Dan's reasoning 20% of 8 would still be 1-2 rounds COM in worst case hopefully, which I feel comfortable enough to cause the attacker to stop.  I would say, carry that spare magazine or pocket knife or other backup plan just in case however, just to be safe since the weight of the P32 is not conducive to pistol whipping.  

I love my P32, get really sick of hearing that it is under powered.  I have read many articals of of bad guys not getting up after they ran into a P32.

Just as a matter of comparison:
 
The caliber responsible for the most deaths in the USA is the .22LR
 
It accounts for more injury then all other calibers..combined.
 
So I don't think I'd worry too much about a .32ACP being underpowered.

Quote from Haku on 11/06/09 at 09:57:11:

The PF9 carries heavier in the front pocket and prints more readily, particularly the butt of the grip, especially if the grip extender is attached.  
 
That said, the PF9 is still extremely concealable in the front pocket and has, as yet, to evoke any undesirable notice when I so carry.  Nevertheless, the P32 is simply more concealable in the front pocket, ceteris paribus, and an observant person would more easily note a PF9 than a P32.
 
Fortunately the vast majority of people are unobservant and those that are suitably observant are more likely to be friendly.
 
Peace favor your sword,
Kirk

Check out the VZ 61 Scorpion.

Click image to enlarge

http://world.guns.ru/smg/smg26-e.htm
Its a 32 ACP machine gun. If the 32 ACP didn't have enough
power it would not of been used by the military and by  
security forces. Yes they had to upgrade to "bigger" guns but
that was due to upgrades in protection/armor plating.
The crack head wont be armor plated so the 32 should save  
your a$$.
 
How do I get the VZ 61 mag to work in the P32???

Quote:

 
Hello,
 
A local gun store has several of the semi-auto Scorpion pistols for sale and though very neat, they are pricey.  You can buy two Sub-2000's for the price of one Scorpion pistol.  I'm probably going to get a Sub-2000 in 40 S&W in the next year, don't have the funds to play with for a Scorpion.
 
Best Regards

+1 on shot placement! I got my CWP 8+ years ago and qualified with my lil P-32. I was up against shooters using S/W 22 revolvers with 6" barrels and out shot them with my KT. SOME WERE NOT HAPPY!! LOL It has been the most accurate mouser that I have ever shot! I don't leave the house without it. In colder weather, I might carry my Ruger SR9 in a shoulder rig, but the 32 is always on deck also. We were shooting cans with 22 rifles on my Daddy's farm a while back, and I hadn't put any rounds through the 32 in a while so I figured, right place, right time. I stepped up with my lil ankle biter at 50 ft and made a can dance...made me smile!