I bought an Allez sport ($750) a year and a half ago to give road cycling a go, and I love it. I have not felt the need to replace it at all. After about 3500 miles, all is still working well on the bike. I might upgrade the wheelset within the year to an open pro/ultegra handbuilt set up, but that would be more of a lust purchase than a purchase of necessity. I do not race, I just ride for fun/fitness and I commute by bike. This is just my experience, and you may find yourself wanting more after a year, but a tiagra/105 equipped bike is plenty of machine. Just don't start reading cycling magazines.