I understand your pain, but the focus on the tools is a bit to much assuming that the grass is greener on the other side. Shooting birds or almost any wildlife, if you get 1 out of 100 that is a great shot, that is doing very, very well. Almost every morning I have sparrows out my balcony door (Less than 10ft) With a D300, battery pack & a 70-200vr and that can't track the dang thing 75% of the time and rarely gets a good or ideal shot. It's not the equipment or needing longer reach, those little buggers move! Shooting from 50-100ft+ away, the chance of getting a great shot is rare. That is why we are in awe of great shots from those who get them. If you follow various pro photogs who are a commercial success, you will note that they only add a handful of images each year. You can bet they shot tens if not hundreds of thousands of photos just to get 5 more great shots they believe they can sell. Being at the right place at the right time has more to do with getting the image than the equipment. Your expectations may be a bit high for what you are shooting.
On the comments of the equipment, personally I see a very little loss of IQ with TCs or a slowing of AF speed. Extending zooms out to their max, the IQ drops a bit but unless you try to crop anything over 75% you can't see it. Although I will say the new Focus tech in the pro bodies and the D800 for the ability to crop certainly would help.
There is a really bad habit of some review sites and others of over exaggerating IQ drops and TCs effect on lenses or racking them all the way out. Many times I just scratch my head at some people's expectations - that every lens that is not Macro sharp is unusable. Pixel peepers and many reviewers focus on numbers rather than results, do more harm than good by detouring people from shooting by making them believe their lens or any other lens is junk. If they actually knew what they were talking about, they would tell people how to compensate for the distance, light, type of situations and wildlife and how the lens can excel in each situation.
When I got into digital, I heard that some rare bird was nesting at a close by pond and it would be a good photo opportunity. I went out early in the morning just as the sun was rising with D80 and an old tamron tele-zoom lens. While leaning against a tree trying to stabilize my body, I heard a light snicker behind me. When I looked over a man with a huge tripod and gimbal head, with a big lens (probably a 300mm f2.8) and a pro digital body walked past and set up his rig about 50ft from me and pointed right at me. The sun rose from behind him, about 30 birds flocked to the tree I was leaning against and pooped all over me.
You see, the tree I was leaning against was further from the middle of the safety of the pond. The birds had been there all week and had picked most of the berries from the "safer" trees. There was nothing obstructing the morning sun hitting the berries on the tree I was leaning against so they all went there. He understood that, been there a couple of times that week, knew where they were going to be, and got set up before it happen. He got dozens of great images - I got shit on. He mounted my camera to his gimbal head, showed me how much easier it worked and proceeded to get some great sharp images. That was almost 7 years ago and the images he took with my camera still stun me.
Great images come from knowledge, experience and knowing the best tools available at the time and how to use them. I have yet to see a great image made with a desire for something that doesn't exist yet.
