7.5" AR-15 Upper for AR Pistol

[LSUTiger]

I have an 11.5" Upper and a 10.5" Upper and I am trying to convince my self to get a 7.5" AR-15 Upper for an AR Pistol. Besides a fun range toy is their any practical use for such an thing? What is the performance of 7.5" 5.56 close to?

From what I have been able to Google:
In terms of velocity (\(1,900\text{-}2,100\text{ fps}\)) and muzzle energy (roughly \(500\text{-}600 \text{ ft-lbs}\)), a 7.5" 5.56 closely mimics heavy defensive handgun cartridges like the \(.357\) Magnum or the \(10\text{mm}\) Auto fired from carbine-length barrels.Cartridge

Counterparts: The ballistic profile drops so drastically that its impact characteristics at close range are virtually identical to a \(.30\) Carbine (historically used in the M1 Carbine).

If this is true, then I would not mind having 30 rounds of .357 Magnum or 10mm equivalent on tap in a small AR package for Home Defense specific applications (25 yard max).

Thoughts?