I'm using a reed switch to detect the state of my garage door. It's connected to an ESP8266 via twisted cables of 1.5m and each line has a pull-up as the signal floats too much otherwise.
Well it still floats and I've been wondering whether it would've been wiser to use the 5V for the pull-up instead of the 3.3V I used. The ESP is 5V-tolerant so that should be no problem.
As far as I know, the higher the voltage the stronger the signal, but I may be spoiled by landlines with high voltage. :-)
Thanks for clarifying.