True, to a point. You can also compare the cold temp properties by either checking the PDS for the desired products, or checking out the viscosity chart at this website.
(Caution - I'm going to make some assumptions here based upon the OP's signature and area.)
But in the OP's South Texas region, I don't know that such a thick product is even warranted, unless some heaving towing is taking place all the time, (which I doubt, given the vehicle in his signature).
I'd think that either 80w-90 conventional or 75w-90 synthetic would be most appropriate for his application. The Amsoil Severe Gear 75w-90 would perhaps be a good choice, given his apparent preference towards high-end products. Or, if he's just dead set on going thicker (perhaps he's racing?), then maybe the Severe Gear in 75w-110?