Appreciate the additional info. and feedback.
Although it's an option (read up on taping pins) I have no plans/intentions to utilize a TC on my 100-400. Because of the dust and other considered factors, I won't be swapping lenses either. I'll have a couple other camera's along as well (GH2 and E-PL1).
By all accounts the 300 f/2.8 lens is phenomenal. Comes with a HUGE price tag and added weight too. If I were to be able to scrounge up that kind of scratch, I'd be inclined to purchase the 500mm f/4 instead.
