kyreb, absolutely minimal advantage under stock conditions. The only real time people 'notice' (=placebo?) use of a fatter spark/larger gap is on starting, esp. when cold, where a larger spark may help ignite fuel a little better. Having said that, a well setup stock ignition, carburettor and choke do just fine.
Fatter spark becomes of use with larger gaps when trying to ignite altered fuel mixtures such as occur with altered carburettion (needles, intakes, porting of head etc.).
The other thing to consider is that the increased voltage will have to go somewhere, leading to increased arcing and sparking across worn/tired rotors and dizzy caps, leading to reduced item life and reliability.
I won't deny however, that the colour is really nice!