In regard to climbing at alititude, I live in Idaho, my home is a 6100 feet. We do alot of hiking from our house up to as high as 9,000 feet. I have also climbed in the Tetons in Jackson Hole, Wyoming. I have climbed the South Teton, the Middle Teton and the Grand Teton. I found that it did not do anything bad with my AS. We went early in the year each time so we were on snow with crampons, etc., so coming down was quite enjoyable (butt sliding) and therefore not as much jarring. I highly recommend it to anyone. There is also a really good 22 mile hike from Idaho to Wyoming which goes right past the Tetons. It is a little lower impact - more walking and some hiking - one good pull closer to the pass, but it is beautiful and a great low impact workout.
On another altitude note, I do feel the effects of storms more severly at our home than at a lower altitude. In fact when we have been on vacation at sea level I feel my greatest. I also have to add that even though I feel like crap when a storm moves in, if I can get my rear end out the door and go for a snow shoe or hike it greatly improves my pain level.
So, I hope this helps with your question..... If you are ever here in the States, the Tetons are the place to be!!!