Why not get the Expert (middle group) Ruby? There is no reason a recreational rider should not have Dura-Ace. The only reason I didn't buy the Dura Ace or Ultegra version of my bike was money. All I want to do is ride 3,500 a year and some centuries, but if my budget had been bigger I wouldn't have 105 right now.

From what I hear you would notice a difference between 105 or Dura-Ace. That being said, most reviews I have found on 105 are quite favorable. I find my shifting to be very smooth, but I have never rode Dura-Ace. There is a BIG difference between my old Sora and 105. Get what you are comfortable spending and don't worry about whether or not it is "too much bike".