I liked the controls better in Arma two with the left shift being the Run or Walk Temporary. When you are leaning around corners and moving slowly it was nice to hold left shift and move around safely with little nudges.
With Arma 3 when you move its an arupt move and could get you killed.
Go back to Arma 2 and hold left shift and inch up to a corner of a wall or house and peek around it, etc.
Try the same thing in Arma 3, its an abrupt move whether you triggered slow or fast with the SW keys.
I think it was better holding shift down and walking around slow and turbo being the W hit 2 times.
Windows 7, 6GB Ram, Intel 920 OC to 3.6ghz on Asus P6T Deluxe V2, with Nvidia SLI 480 GTX.
Close this after playing more I agree the default keys are fine. Just have to get used to them. The arubt movement I was next step lower than kneeling and was causing the issue.