That was fast. Retro, thanks for your thoughtful answer. About performance, I wonder what would happen if we put someone like Lance Armstrong on a bike with the 2200. Would he be much slower because of that? Would the components break because he is stronger than an average rider? I doubt that. I understand that in professional races every second count, but outside that it all feels strangely like a "brand lust" and "component status" than real benefits. Like component weight. Do I really care if my deraileur weights 50 grams less? Why should I? As you said, there's a really crazy difference in prices from one to another. Sure, I wouldn't mind if I was on a race team and my sponsor gaves me the cool parts for free, but in everyday life it looks like an overkill.
The thing that worries me the most is realiabilty and durability. I had a bike with Sunrace parts and, boy, I hated that crap. I had to tune the deraileurs every 100km. The damn gears jumped like kangaroos. The changers couldn't hold still. I was so disgusted by it that I tossed the whole bike away and bought a new one, the one I ride today, with Shimano parts.
Today the ghost of that old bike still haunts me, to the point that I'm afraid to use something too low on the line up of any brand. I read that Shimano makes only good parts, from the lower line to the top one, but I fear of buying something like the 2200 and see my bike going Sunrace all again. So, Sora or 105.
The things I really care for now are: will this part be realiable after two thousands of kilometers? Or will it be a headache for me? Will I need to tune the deraileurs every time after a longer ride?
Too many questions, too little time... But I'll keep looking and asking around.
Oh, yeah. I forgot to tell why I'm building a road bike, which may help the discussion. I got tired of trails and realized that asphalt is my thing now, and I want to ride something different and fast. Also, the roadie will be my new commuter. In the future (a year from now) I want to race (not necessarily win), but that's not my immediate goal.