I'm late to the game on this post, but I've had mixed results with my gear.
By day, I was working as a photojournalist with a Washington Post Company, and on the weekends, I'm a NARP Ambassador. I commute to and from DC on the MARC. I have had no problems with Amtrak at DC Union, but have had major issues with MARC employees when just banging off a shot with a small Fuji X-100 camera.
Despite being a WAS NARP booth kiosk attednant and am regulary seen at Gate G, as well as having my NPPA badge on my neck while o nthe clock for the Post, there has been issues with the MARC guys.
With that said, I have had no issues with my professional Nikon gear (D3/D4 and 24-70 2.8) on Amtrak trains or with personnel, even having Amtrak crew want to have their picture taken or offering to take my picture in front of Acela's and LD trains on the platform.
So, I think it can be a crap shoot depending o nthe level of training personnel has had on policy.