..right up to the point that some jerk with failed brakes and invalidated insurance drives into the back of you at lights.
If you're lucky! You might be t-boned at an intersection; though in the UK it might "sideswiped on a roundabout" (wish we had more of those here in the US).
;D
GordonEndersby: It sounds like you know what you are doing, but please be careful. I know that the booster is only one section (and is there to help - not replace - so pump the pedal if you have to, I suppose!). If you can make it as safe as possible, and it won't invalidate your insurance...
Well - good luck with finding the problem!