What benefits will being Special Forces offer for my career progression?

Any MOS you pick will allow you to have a successful career and retire at 20 years. Some of the smaller jobs don't have that luxury. Any combat arms MOS (Infantry, Artillery, Cavalry, SF) will allow you to make E8 in under 20 years and E9 a little past that. If Career Progression is your primary focus, nothing promotes faster in any branch of service than Army Infantry.

The Ranger RGT promotes NCOs faster than most (or at least it did in the 80s). If you plan on remaining within the Special Ops or are planning upon passing into the Intelligence Community at some point, it can be a golden ticket. If you have your 'long tab' and are no longer assigned within the SO community, it helps or hurts depending upon your individual rater and whether or not they feel threatened by your achievement.
Special Forces can and does (most of the time) signal to a potential civilian employer that you are a team player, task oriented, and exceptionally well motivated. If your potential employer is very liberal or progressive (and let the news media do their thinking for them), they "may" consider you to be a potential Rambo-esque PTSD burnout and work place assassin. In this case it will be a hindrance.
A negative reaction is not common, but will depend to a certain extent on how much you talk about your experiences. The less you talk the better off you will be with everyone.

What are your goals as far as your career? Are you looking at making SF a career for you in the military? Are you looking to use it as a stepping stone to elsewhere to include the private sector and/or law enforcement? Need a bit more detail.