I use trueprotein. Great customer service and totally customizable product if you want to geek out. No idea how it will treat your GI tract, but I have never had problems with any of it. I get 5% off with my discount code as well-- slh332.
S. Emile Hughes
Current Lifts (December 2010): BW 166lbs; 285lb Bench Press; 315lb Squat; 175lb Overhead Press; 405lb Deadlift; 205lb Power Clean