It's not a lot less in rotating weight, but it is lighter rotating mass, sure. Personally, that would not be my reasoning, but obviously it'll work well for that. Like I said, most are using a 2 disc Bully. That's what I'd be on.
Now, the smaller plate classes would have an obvious advantage by going to the single disc, as well as it not being as hard on crank flex when it engages. The extra weight, coupled with the hard engagement that most racers want to feel, really plays havoc with crank flex (specifically cast clone cranks.) Most people I talk to are on the better cranks now, so it's not as much of an issue, but they still prefer the single disc on their small plate clone stuff.
Anything we can ever do for you, don't hesitate to call the shop and ask for me.
Thanks,
Brian