[Opinions] Re: Kirsten/Kiersten/Kjerstin
I prefer Kiersten or Kjerstin. Really, I like Kjerstin better, but I like Kiersten for the same reason you do. I also like the -in ending better than the -en ending, so that's another point for Kjerstin.
Kirsten would definitely be misread as Kristen. It's also mispronounced as "kur-stin" a lot, rather than "kyeer-stin."
Overall, I like the name but not enough to use. It's a nice name that I think ages well.