As someone whose everyday handwriting is italic, I have long wished that Pilot offered their SU or MS nibs on the Custom 823. Now, apparently, they are expanding their nib offerings from the usual F, M and B.
One Italian vendor reports the Custom 823 will be available through their shop with a newly issued <S> for "signature" nib. This sounds like a stub, from Pilot's description. Another European vendor reports the C823 will be available to him with a Stub (<SU>) nib in the May/June time frame. I don't know if additional Pilot #15 nibs are in the works.
David