Vixen alloy front hubs anyone?

[Moto]

Having almost finished looking into wheel / tyre weights (previous post) I'm now looking at differences between cast & alloy front hubs. A couple of questions for anyone who's already been down this route :

1) Sourcing of alloy units - where from and are they unique to Vixen's or will Triumph ones fit.
2) Weight saving - one source states 1.8kg vs 4.7kg where as another states a 1kg saving with alloy
3) Any feedback on whether the difference when driving is worthwhile

Moto