Hey guys, here's a newb question that I'm hoping you can help me with...

How does an older Ultegra (6600 from ~2005) group stack up against the current Shimano groups on the market? Basically, as innovations and material improvements have been identified over the years, have older group sets been matched performance-wise by lesser groupsets of the newer generations. For example, would a lightly-used Ultegra 6600 set from 2005 be equivalent (weight, performance, material composition) to a current Tiagra or 105 set?

Here's why I'm asking...
I have a bike that is pretty much fully equipped with Ultegra 6600, but the frame is junk and doesn't fit me correctly. I have an opportunity to get a newer bike (2011 Cdale CAAD8) that is equipped with Sora/Tiagra components. I'm assuming that switching out the components to my Ultegra set would be better than using the Sora/Tiagra, but don't konw for sure...

THANKS