Thanks David. I have seen others using the Celestron (or Meade) .63 reducers on refractors and getting good results. Although these were made for the SCT so I have to ask..how can this be?
Gary Honis did a
test of reducers with his 127ED. The Celestron .63 and the TV .8x (for 600mm scopes, not the RFL-4087 unit). He showed the Celestron reducer to be quite good. The TV unit (similar to the WO II) was asking too much for the scopes FL of 952mm. This backs up the IIS test you linked to.
But I get the feeling the best one is the TV RFL-4087...although not the cheapest. Although I'd love to hear from users of the WO type VI reducer/flattener.