Note sure what "out-of-date" is. On Denali we didn't start taking it till we were above 14,000'. Prior to that we had no problems. In our push from 14,500' to 17,000'+ I felt fine but one of the others in our group started getting AMS or beginning HACE. In our haste to get down I frostbit five toes. He recovered when we got below 12,000'. Was my frostbite related to increased urination from the Diamox or from the -44 temperature or from our lack of breakfast/hydration routine or a combination, I don't know. I have never used Diamox since and I've been over 17,000 and 18,000' but taking time to acclimatize.
This is an except from a 2006 draft by the
International Society for Mountain Medicine on
An Altitude Tutorial
http://www.ismmed.org/np_altitude_tutorial.htm
We do not recommend acetazolamide as a prophylactic medication, except under the specific limited conditions outlined above. Most people who have a reasonable ascent schedule will not need it, and in addition to some common minor but unpleasant side effects it carries the risk of any of the severe side effects that may occur with sulfonamides.The dose of acetazolamide for prophylaxis is 125-250 mg twice a day starting 24 hours before ascent, and discontinuing after the second or third night at the maximum altitude (or with descent if that occurs earlier). Sustained release acetazolamide, 500 mg, is also available and may be taken once per day instead of the shorter acting form, though side effects will be more prominent with this dose.
This is an interesting article in that it also talks about AMS, HAPE, HACE and other altitude related things. From what I can recall, I've only gotten AMS once and that was on an evening drive up to Whitney Portal followed by a night hike up to the base of Mt. Russell without sleep, 1,000-14,000' in approx 10 hours. I had a splitting headache and my friend also vomited near the summit. From the readings I have done, some people to alright without Diamox while others on the same climb suffer with it. When you say you found it effective, how do you know that you wouldn't have been fine without taking it. And for most of our SAR missions, we are off the mountain within 24 hours anyway.
Rick M