LSA plays a big role too. I had a 220/230 duration cam on a 114 LSA. pulled 14" of vacuum at idle in a 318, then a 222/228 cam on a 107 LSA in a 360, idles at 9"

with my stick shift transmission, the 9" at idle is not a problem for my power brakes. blip the throttle a little after starting the engine, and I get enough vacuum built up that I can manuver around in the driveway without having a hard pedal. downshifting the transmission while slowing down creates enough vacuum that I can get 3-4 full pumps of the master before vacuum is depleted.

with only 9" of vacuum in the last 4000 miles of driving, not once have I had a problem where my brake pedal was too stiff