Disco 1 Electric Brake Vacuum Pump

Has anybody fitted an electric vacuum pump to their Tdi Disco 1, If so what sort is suitable, is a vacuum reservoir necessary? I'd like to get rid of the engine driven one.
I can buy one from a Volvo or I believe some of our GM products here are fitted with similar type units, thoughts please.

Electric pumps are not normally very powerful, so "top up" the vacuum level slowly. The booster acts as a small reservoir, so be guided by whatever the vehicle manufacturer did on the vehicle youre taking the pump off. If they thought they needed an additional reservoir, so will you. If they didn't they were obviously confident the pump output was good enough.