the biggest weakness of the vacuum system comes when you up the cam duration and the vacuum drops. Maybe I should say danger as well as weakness. Cars are hard to stop when there is little vacuum stored in the booster. I remember those days well.
Hydroboost removes that problem plus it provides more pressure to the brakes than does vacuum. This was also true of the PowerMaster.
For a street car, with a stock cam, vacuum is fine....
Norbs should start selling hydroboost kits for you Canucks....TB3 would never put together a write up/pictorial for us yanks. These days, i suspect one can put together a HB system for not much more than the rip off prices of a vacuum system.