Hiiiii...i just started my MBA 4 months ago, students don't care if you stammer or not as long as you are a good team member. I haven't told teacher upfront that i stammer as of yet because I don't it has impacted. May be if i was in college i would have. There is gonna be a lot of presentation , be prepared for that. Can't say about placement as of yet but i can tell you for company also it doesn't matter having worked in IT industry for 2 years.