If you shoot at night non tripod stuff, the 2.8 is helpful. It could mean shooting at 3200iso vs 6400iso. With the 1.3 stop. Which will greatly reduce the noise with an APS-c sensor. But if you do not shoot in the low light to often. F4 works fine.
Super Frequent Flyer, no joke. Ex Patriot and loving it.
Canon Eos 60D, T1i/500D, Eos1, Eos 630, Olympus EPL-1, and a part time Pentax K-X shooter.