I found them much easier to use, especially when needing to open or switch between faders quickly.
Reversed quadrant faders were the best, ergonomically -- that up and over action follows the natural movement of the wrist very well -- but reversed flat faders are okay.
To open a fader to a set level, you just drop your thumb in front of the required fader level, and then use your 3rd/4th fingers to pull the fader up to the thumb. Fast, accurate and comfortable.
It's not as easy to place your 3rd/4th finger beyond the mark and push the faders up with a thumb. Possible, of course, but it's not as comfortable or easy to do, and I don't think it as accurate or precise, either.
For semi-static music mixes the faders direction makes little difference, but for a fast news or panel programme it really does!
And then there are other practical benefits, like not accidentally knocking a faders open with your jacket sleeve...
