MagicRide
My very first SS wing was the i76 and I was blown away with the performance but it was fairly windy. I couldn't believe anything would be better, then the i84 came out and to be honest the i76 took a back seat unless it was consistently over 16 mph. I do still go back and forth between the 2 wings.
I currently have the i99, i84, i76 and TC68 and they are all phenomenal wings for each given wind strength.
In Dallas we have a range of riders from 155 lbs to 205 lbs, last Sunday the wind was 10-18 mph with 5mph holes.
5 of us was on the i84 and one rider on the i99.
With regards to the local conditions you described, The i84 will foil up quicker than the i76 if you use the 48 rear wing and the i84 will definitely keep you gliding through holes much longer.
Don't worry about the wing being bigger, it actually gets slower the windier it is (like a speed limiter)... and again at 9-15 mph with a 6.8 that really is what the i84 was designed for.
At your weight you will comfortable using the i84 up to 20mph, then after that change to your Gamma.
infinity 84 video