V-Synth XT lol
I've never found anything other than maybe the pitch shifter and or some lofi effects that does anything really transformative AND musical for vocals on Fan-X ... Of course you can try, but there are much better sources out there ...
The afformentioned V-Synth XT is the best digital vocoder (as well as a great vocal designer engine) out there hard or soft imo and to boot you get a V-synth and Roland D-50 as well in a realtively small footprint with a realy good unser interface considering the limitations ... Awesome piece of kit ...