Look, a brifter is a brifter, some are very expensive and work better then others, but they all shift gears. The Sora and 2300 have thumb shifters instead of the paddles under the break levers. But its not going to make you any less "aero" or slower.

If you have the money, it will be worth it in the long run to buy the Tiagara and even better. If not, then dont worry and ride.