I was reading somewhere that they are very similar to the Fire gene. Even so in the fact that the 'super' form is a Black Eyed Lucy.
I'm also thinking, don't hold me to it, but it shares a 'complex' (hoping that's the right term) with the Fire much like a Lesser and a Mojave. You could breed a Fire to a Sulfur and get a BEL as well.
I don't have any, so I'm no help with the pictures.
In my opinion, the most stunning of the Sulfur combos so far is the Super produced by David Reid, the originator of the Sulfur. I am happy to say that I now own this guy's father, a Sulfur Mojave, hope to produce a super like that myself someday.