I've been pretty happy with my BTR Kit and using an RPM window switch.
Everyone has their own opinion as to which setup is the best.
The main thing is make sure the jetting is right on the dyno.
I run a "hybrid" system whereas I have the NOS5180 dry kit, but use the Vec 2 to add more fuel with the program card designed for the NOS when added. If I was to drive the car on the NOS program without adding NOS, it would be VERY rich at the higher RPMS. I find this to be the safest, at least for what I want.
You can put a pressure switch on the line out of the fuel solenoid. This would then close the ground to the nitrous solenoid. It would accomplish two things: shut down the nitrous if the fuel solenoid or pump fails; give the fuel a little head start, this is important because it gets rid of the lean spike associated with nitrous.