I think naming it a sulpher from the begining was the right thing. They are different lines with different looks and untill they have even been proven compatable one must consider that they may not.
It may come down to the butter lesser thing. They are different lines of a similar morph and the different names tell you what the lineage is.
All lessers come from Ralphs line and butters are different lines. Ralph himself owns both and feels that way.
All sulphurs come from Davids original animal and are a different lineage than fires, even if they are proven compatable they still come from different genetic lines which i think is helpful when discussing genetics. I have seen both and to me fires start off and stay lighter than sulphurs.
I like knowing as much as I can about genetics and lines so I can pass on the most accurate info to anyone inquiring about an animal I am working with.
Thats my take on it.