I had fusion surgery 7 weeks ago, but am still not walking on it, so I don't have lots of information yet. It took me a year and a half to make the decision, hoping to be rid of the pain. My doctor told me my fusion can be converted to a replacement later, but some say that's not possible. There's a lot of guessing in this.
I have started a Yahoo Group on this subject, with 50 people (from Europe and North America) discussing all these issues. Go to http://health.groups.yahoo.com/group/anklefusion to join.