Molasses can really mess up a beer if over-used. It can impart a harsh minerally metallic taste at worst, and at best it seems to add a sort of licorice-like sweetness. It's one of the things that I think makes New Planet's Pale Ale taste twangy and metallic...NOT a good complement to sorghum! If you want a dark-colored syrup, try Belgian Candi Syrup, it works really well in stouts and dubbels. Or try burning some honey--that adds TONS of color (like half a pound of it will turn a beer pitch-black) and can impart a roasted and smoky flavor. Don't overdo it, though--I've yet to make a nice balanced beer with burnt honey, in fact two of them end up dumpers. One thing I've learned is that unlike when brewing with raw honey, you actually want a light-colored clear filtered and processed honey, because the same stuff that makes raw honey flavorful makes burnt honey harsh and rough around the edges.