I know nothing of them personally but I am aware of
a petition to ban 'the indiscriminate import of reindeer for profit' on the basis that they will suffer unless managed correctly - which, the petition claims, means being in the Cairngorms. Whether or not the petitioner is connected with the herd already established in the Cairngorms, I don't know.
A veterinary article is referred to, but I can't get access to it. Someone with a gmail account may be able to read it and comment?