Nitrous with a 4spd

after doing a little bit of research, it seems that most nitrous kits come with a full throttle switch which actuates the nitrous only when at full throttle obiovusly (when the secondaries are opened)...If you are not powershifting (therefore letting off the gas to clutch and shift then back on the gas) would having a full throttle switch put stress on the engine when you get back in the gas, or would it be just like letting off the button with your finger while changing gears? also, this may sound dumb, but why would you set your limiter a couple hundred rpm higher than the high limit of the window switch?