Originally Posted by
jmeb
I believe the only differences between a 6XX and 7XX series during this time are a) 7xx series had full 531, while 6xx series only used 531 for the main triangle. So the 7xx series will be a couple of ounces lighter. Unless you're really fit I doubt those couple ounces (less than 1/2 a pound) make much a difference and b) components. Components don't really matter in this case because he'll be doing a new build for you, so whether they are 7xx series-grade or not depends entirely on the rest of the build.
So what really matters is what components he is including in the full build and how much cash he expects you to lay out on top of that. If he is building with better than original components, and expects very little or no cash, it could be a great deal to you. Realistically I don't think you'll notice a huge difference between a 620 frame and an RB-1. The Rb-1 is a bit sportier, the 620 frame a bit more versatile and better for light-touring in the future.
Like I said, many people would be happy to trade a frame for an entire bike. I personally would rather trade a high end frame for an equally high end frame because a bike represents more than utility to me, and the mystique behind the decals on a high end bike represent additional value in my eyes. If the 620 were really so indistinguisheable from the RB-1, then I suppose we'd see a lot of people flocking towards the RB-2 as well. But that is not the case. There is more to a frame than what it is made of, even if my butt can't tell the difference.