I find my 7700 brakes to have a bit of flex - just not enough to matter. The '96 Chorus brakes I have on a different bike seem a little stiffer. Both stop the bike. For a DA bike 7700 are easier to get pads for than 7402, but aren't as conspicuous in shape as the 7800. (But the 7800 are also nice looking.)

There was a time when ultimate power wasn't the goal of a road brake.