Just talked to a Sigma rep today at a demo day and the other version of the 150-600 (not the sport) is due to ship at least in limited quantities the first of February. He said they intend to ship both mounts not one and then the other.
Steve ( who isn't buying any more camera equipment till after Christmas anyway)
Did you get any indication of the price or weight of the "Contemporary" lens?
Making comparisons between the Sigma "sport" and the tamron is a bit artificial given the disparity in weight/price, but this info is currently not published for the contemporary.
Interesting times in the realm of 3rd party zooms!