Yes brother response time difference can be felt. I had brake booster in my ex-Mehran, my better half used to drive it occasionally. I sold that car for some reason and bought new one and I haven't installed brake booster yet (though I've planned to get it done on Saturday), my better half drove new one today and while braking the comments were: "yeh ruk kuin nahi rahi"
I've kept my current one with original size, steering is very light plus good economy. I used 165 in my ex-ride, and then 155. Difference was clearly noticeable.