"Do I really need a magnum?" Yes..... it allows you the option of shooting either/both .38spl and .357 magnum from the same gun.

I carry 125gr .38sp +P hollow points in my Burb of the Burgh...... 158gr soft point .357 when hiking in Penn's Woods.

IMO a 4" Model 686 is the best utility/duty/general purpose revolver one can own...........for concealed carry a 3" 65 or 66 is the perfect balance for a gun that gets carried a lot and maybe shot.

Edit: I don't subscribe to the "one shot stop" theory..... I'm a firm believer in the "double tap".......