I use my 6" f8 achro for planets and can say it's fantastic. For the moon and Jupiter I use the Baader semi-apo filter and it removes the violet fringing brilliantly. Never use the filter on anything else. The image is really close to what I see in my 4" ED f9 refractor but brighter. I have never looked through an 8" Cas so can't comment on that part. Add bino's and
Of course a 6" refractor is a large heavy thing.
Matt