« on: September 26, 2013, 10:02:40 AM »
Are you using a neck strap or a shoulder strap/holster system to carry the gear? 2 kg around the neck is a lot, but it's a lot easier with a strap system (i.e. BlackRapid).
The 70-200 II is the best choice for nature, people/pets and events, and yes, IS is almost a necessity especially if you want to use it for indoor events. I often drop the shutter speed to 1/50 to 1/100 at 200mm to decrease the ISO. Yes, modern cameras can get you higher ISOs, but the DR is compressed at higher ISOs and highlights are more easily blown. Add bad lighting, and you want as much lattitude with the files as you can get. There is a big difference between working with ISO 3200 and ISO 12800 files. The 70-200 II also takes extenders well. With the 1.4x, it's nearly a match against 70-300L and it is a stop faster. With the 2x, it's a little worse than the 100-400L, which is pretty good performance.
The 70-300L is the best choice for travel. It's compact (shorter but fatter than the 70-200L f/4 IS), which makes it easier to pack in bags (vertically), and it easier to carry when the lens is locked at 70mm. You lose a fractional stop at the same focal lengths to the 70-200 f/4 IS, but outside, it's usually not an issue. Servo AF is not as good as the 70-200 II's.
If I could only have 1 lens out of the group, it'd the be 70-200L II. IQ is good and it focuses well. Only negatives are weight and price. I started with the 70-200 II and brought it everywhere. Later, I picked up a used 70-300L specifically for travel (great as a zoo lens), but I still use the 70-200L II more because it is better for sports, portraits and indoor work.