This new legislation is very unpopular in France and does make driving on secondary roads a real pain... you're always looking at the speedo. Until after the holidays, you'll probably get away with a warning if you're under 95km/h but after that unless it is repealed in the autumn they'll start dishing out fines....
It was all based on very dodgy research, and is unlikely to make any real difference to the accident rate, that is usually down to people over taking in a dangerous spot, tailgating, driving drunk or under the influence. Those that didn't take any notice of the 90km/h will not do so now it's 80...
It has been suggested that extra attention needed to stay at lower speeds, watch the ever changing limits.. (can go from 50 to 110 to 70 in the space of a few kms..) will lead to more accidents...