For me, it was a matter of money. My friend offered me the Cross Check at a price I couldn't resist.

cinco, I find that brifters make riding more pleasant. I'm fine with downtube friction shifters, too, but brifters are more fun. My 3x9 Ultegra setup has very closely spaced gears and shifters (brifters) right near my hand, so I can shift very, very often, which improves speed and efficiency. It may not be a huge improvement, but the improvement is pleasant. It also allows me to maintain a higher level of exertion. Contrast it to a 3-speed: with a 3-speed, the gears are way-far apart, so I shift down and reduce my effort to match the gear I'm in. The reason I choose a 3-speed is that it exposes the difference than comparing my 3x9 setup with a 2x7 setup.