Hi Ian,
welcome on the forum. The Oympus Mons is a very warm boot, suitable for all the high mountains. You might want to compare with similar type boots, for example the Millet (One Sport) Everest. I am sure there are more, but have not looked into it recently.
As they do not adjust to your feet, you need the one that is not only warm, but fits the best as well.
Both will be a bit overkill for Elbrus, though your feet will never be too warm

and if you want to climb Denali, Vinson, Aconcagua or Everest later, those bots will make your feet thankful.
Problem is they are all expensive, but cheaper than a toe operation..
Cheers,
Harry