Sol,
'Soul' has done a bit better for me but I don't like it as well as 'Silver Song' for things in that color range. Am hoping one of these new ultra-wide seedlings from 'Silver Song' will be more towards wulfenii too. They do seem to make bigger rosettes.
I also have one that is blue and pink and makes very large (10" +) rosettes with the wulfenii form from ('Silver Song' X 'Polly Bishop') X self. It is a prolific increaser too. That one will be marketed. I finally got a good crop of seed from it too.
Kevin