It's around one stop slower than similar lens (Sigma: 150-600mm F5-6.3 2100g; Sony 200-600mm F5.6-6.3 2115g; Tamron 150-500mm F5-6.7 1725g), interresting to know the weight. I think it would be the most portable one and smallest filter diameter (e.g. 67mm)
Great to see this addition (I think...