I am going this afternoon to get an HK P2000 that comes with both .357Sig and .40S&W barrells. I carry a .40 now, but was wondering which would be better for a defensive round. Is there too big a chance of over-penetration with the .357Sig? Also, since the barrell is the only part you change out, what difference in POI can I expect between the two? Any input would be greatly appreciated.