My local Samy's Camera had the Sigma 150-600mm f/5-6.3 DG Sports lens for rental, so I took it out for a spin. The Contemporary version of this lens wasnt up for grabs.
ISO100 600mm, f/10, 1/640s
ISO200 210mm, f/10, 1/80s
I havent had time to ID the differences between the Sport and Contemporary versions of this lens, but I agree this thing is big and heavy. The Canon 100-400 I rented last time could at least fit in my bag, but this Sigma lens has its own bag! As expected, I'm probably going to need a beefier tripod as this setup is prone to wobble, but I can work that out.
I'm also running into some whitebalance issues at 600mm, when subjects are really far away (40 miles). Not sure if its just me, the UV filter, or the lens.