I hit (rocks) and bent (axle wrap) my 52's so bad that I'd be afraid that 64's wouldn't have lasted even an hour under my buggy.
You can get all the flex you need from 52's, to me its more about making a more capable vehicle and not who can score the most points on an RTI ramp
Here's my buggy from years back with 52's front and rear (with the stock rear shackle setup

), all four tires are still on the ground