I am looking to buy a pair of La Sportiva Olympus mons. However I am still unsure what size to get even after trying on several different sizes. My usual size for mountaineering boots is 44.5. For the Olympus mons I was thinking about either 46.5 or 47. The 46.5 fits quite well and my heel does not move much, however I am not sure how much feet swell at altitude and how this may affect the fit? With size 47 my feet have a more room (so there is more reserve in case my feet swell), however my heel moves quite a lot.
Does anyone have any experience with how much reserve is needed when feet swell at altitude?