On the beefalo drum on my cb450 project, I had a local machinequote:
I agree with you for stopping power, but if you can have more stopping power and save weight, what would you take? The weight of most these drums is in the lining. The small drums have wider brake pad surface, more lining. It's almost a full half inch wider.
shop turn down the lining a little, and dropped the weight
significantly. Also had them drill three small holes per web
to lighten it even more. With an aluminum rim, they're very
nice. Reduction of rotating mass, and all that...
So, yes, having narrower lining further from the hub will give
you better braking power compared to wider and closer. And if they
weigh the same, the choice is obvious.
You can also cut up the backing plates and put screens over the
areas you cut out. I'll have to scan some pictures that I took in Daytona...