I ride the 2006 version of 105 with an Ultegra rear, keep everything lubed and tuned and she shifts like a dream. I have over 5,000 miles on my bike right now and have only had a basic tune up and a routine bottom bracket service. My husband rides 2004 Dura Ace and said he thinks my 105 shifts *almost* as crisply. Save the money for spoiling yourself with new bike clothes unless you are hung up on labels. In my mind it is like spending less on a Toyota instead of Lexus. There are perks to the pricey one but the other is still a nice ride you will enjoy.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan