Denny, we in Aus don't have the highest mountains but I have travelled from sea level to a ski resort called mount hotham which is 6000 feet. I never had to do anything adjustment wise but I do have thumbscrews if need be.
So unless your bike starts running a bit rough, I wouldn't be concerned about it, and the worst I guess that could happen is the idle running a bit rough and you can sort that out with the thumbscrews.
I suppose if you had your bike tuned to sea level and then you were riding high up into some descent altitude, then perhaps there might be some idling issues.
For instance I live at around 2000 feet, and go down to the coast and have no issues, and likewise have gone up as far as 6k too with no probs. Keep in mind the tuning at 2k will only give a differece of 4k. If I was at sea level and then went to 6k there might be a difference but I don't think so. In fact I've never heard of any circumstance yet where anyone has had to adjust much as they travel from here to there, unless it's a long long way going up and down and round and round etc etc.
So I wouldn't think there was much to be concerned about but perhaps someone else will give their viewpoint from similar experiences so you can ascertain what you may expect.
