I used the thumb-shift soras on my bike up until yesterday (about 3000 miles) at which point I switched them out for Ultegra (6500) and, I have to say, it's a big jump in shift performance. Not only is it now possible to shift both up and down from the drops, I find that some shifts are so smooth as to leave me wondering whether I shifted or not.

Though, on the flip-side, I do miss the visual indicator. Much like staring at my computer keyboard (still) while I type, despite typing upwards of 100 WPM these days, I did still look at the gear indicators on the sora shifters (even though I kind of knew what gear I was in.)