With the small platforms that the .380 is available in (LCP, Keltec), to me it doesn't make sense to carry a .32 based on saving an ounce or two.
As mentioned above, most of these arguements center around why carry a .380 when you can carry a 9mm but I digress...
As far as SD rounds go, the .380 gives you a lot more options than a .32. I feel confident carrying hollow points in a .380 but I tend to stick with FMJ for a .32.
"He who laughs last, laughs dead." Homer Simpson