They are 2 different animals completly. I would have to say I like the Ridgid because of the beefier feel. I know quality doesn't always equate to the weight of an object but this is imbedded into my psyche.
The Ridgid Micro is a 3/8" drill chuch and the Bosch PS40-A is a impact driver with a quick release chuck. They weigh roughly the same in my hand.
I had my wife and her girlfriends try them side by side and all the ladies liked the Bosch better. It seem to fit in their petite hands better. Something about the Ridgid colors reminded them of a bad Halloween Candy Corn incident. The blue Bosch had less of a "tool like" appearance and that was visualy pleasing to them. The Bosch does light up the workpiece better also.
Stay tuned to next weeks exciting episode of The Girly Toolbox: How to Hammer Your Man