The Briess Sorghum Syrup is from the head of the grain containing maltose (what most people use for GF beers), and the Sweet Sorghum Syrup you see around is from the cane. They are different. However, it seems you are talking about the latter? I have used sweet sorghum syrup in a couple of my brews, and plan to use it more. I used it in a brown ale but that ended up getting very infected (makeshift airlock blew off, it was open for days in an old cellar). However, I used it in my Monolith RIS and I think it adds a unique flavor to it... I think. A lot of things went into that beer. I'm planning on brewing that brown ale again soon to see how it really shows in a beer. I'm not sure about the fermentability of it, although I would assume it's similar to maple syrup and molasses.
I get the raw sorghum, 100% sorghum, no corn syrup or anything else in it. I would boil it before adding to the beer.