I totally agree with Rob and it really depends on where you live, too.
"Humidity is over-rated" (quote by the Chameleonaire himself, Mike M. at FL Chams...) I used to think he was nuts saying this and thought it was easy for him to say this because he lives in Florida (i.e. humidity). However, if you have proper supplementation, proper gutloading, proper caging, etc. AND proper hydration, you should be fine even with a little less humidity. For the last couple of years, I have been keeping my chams at around 50% (give or take) and have had no issues. So yes, it is over-rated. (Disclaimer: this is based on my experience with several species and based on cham keeping in Illinois only.....)