I think so within limits. Apple sometimes limits the ability to downgrade at a certain point. Never had that issue as every upgrade has gone relatively smoothly. I think the ones who have that issue are those who like to jailbreak, of which I suspect you would be one. Apple tries to break the jail breakers with successive iOS updates, which is when the jailbreakers start scrambling to downgrade. don't now for sure, because it's not an issue I've had to deal with.
Ask the Internet.