I believe that the only thing you have to watch out for with testing is that you are not supplementing with folate as this can mask the results. There is some measure of argument as you have probably discovered over what levels are the 'right' ones, with advice differing from country to country. The Pernicious Anaemia Society (PAS) website seems to indicate that these levels may be misleading in people with B12 def. or Pernicious Anaemia and that much higher may need to be reached for therapeutic results and sustained repair of any existing damage. There seems to be little info about, and a lot of ignorance of PA among people who think that one treatment fits all. The evidence of people with PA seems to differ. I am in the learning stage with this too!