As you can see from my signature, I have the 70-200 f/2.8 VR, 300 f/4 AFS and my newest acquisition, the Sigma 500 f/4.5 HSM. I also have 1.4, 1.7 and 2.0 TC's. I'm having a hard time rationalizing the 300. The 70-200 will give me 280 and 340 with VR and if I want longer I can use the 500, but not handheld. But I probably can't use the 300 with the TC's handheld anyway. Any thoughts on why I should keep it?