I'm not sure what potential risks portkeys could have over long distances (in Canon Potter, to say nothing of MOR Potter) so this might not actually be evidence of trickery on Santa Claus' part

Canon presents it as very safe. It's used internationally; I believe we read in Goblet of Fire of people coming from North America to Britain via portkey and possibly even further. No risks are ever seen or mentioned (in stark contrast to apparition or Floo or broom). It's used in preference to any of the other methods for children going to the Quidditch World Cup, further cementing its apparent safety. And so on. The downside seems to be that it's somewhat unwieldy and inflexible, and not too great at moving lots of people from point A to point B (witness the Hogwarts Express versus the the difficulties Harry & co. have with their large portkey group going to the Cup).