I just posted a similar thread in the mountain bike forum (but this XTR, XT, etc...). I recently traded in a bike with some extra money and got a new mountain bike and a new road bike. Now to do this I had to settle for some lower end components. On the road bike, this meant 105's on the back but everything else being Tiagra. I was expecting some rough shifting or maybe reliability issues but was pleasantly surprised that everything works VERY smoothly. I haven't had a single issue over the last coulple hundred miles. So I asked the guy at the bike shop about this and he said that components have gotten to the point where most decent stuff works great. And that, say, a new Tiagra component works about as good as an older Ultegra or 105. And that the main difference between them is a few grams in weight. And that the reliabilty and function is generally about the same. I have seen this first hand and it makes me wonder why so many people are SO big on spending all that extra money on something like Ultegra when 105's and even Tiagra's would do it pretty much just as well. Now I understand that if you get a nice bike it will have the higher end components but other than that you would think it would'nt be so saught after.
What do you guys think? What have been your personal experiences?