If you notice that you're not shifting much and rely on 3 speeds 80% of the time, then no need to upgrade to Ultegra either. The extra money you pay is for lighter components and slightly smoother shifting pieces. I have both 105 and Ultegra, and I can only tell the difference when I'm pedaling hard with a group up and down hills where shifting is constant. But for my long rides with very little shift activity, doesn't matter one bit.