Tricky to go below 1/200 at 400mm, that lanc was a surprise popping right out behind me too straight after the F-15 demo!
I've had that issue before with my pictures appearing dark on other monitors, but I have a couple of well calibrated dell U2410's in my office and colours are great, looks good too on my dell laptop, but very dark on a 22 inch samsung. I can really only judge by how they appear on those and since the U2410's are calibrated/supposedly have the best colour and are the most expensive I make sure they look good on those first and foremost, and in my experience going from those to print has always helped me a great deal due to their large choice of colour options and tonal reproduction.