The 2 year home residency requirement will prevent you from applying for a green card (adjustment of status) unless you obtained a waiver of the requirement at the time of filing. However, it is unlikely that you will be subject to the 2 year residency requirment unless you receive a stipend for your training. Germany is not listed for most training fields (if at all - need to check-) on the skills list that triggers the requirement .

Read more at: http://www.xing.com/app/forum?op=showarticles;id=5871031;articleid=5873099#5873099.