I think you chaps who do visual are missing Troy's point here. He is more than likely talking about imaging which is a whole different kettle of fish to visual work. The focal lengths involved in imaging range from 8 metres to 12 metres. An 8" scope will struggle with those focal lengths to produce a bright, well exposed and detailed imaging free of artefacts.
Try looking through a refractor at those focal length and there will be a similar related views. At low powers in my C14 on good nights it can be a visual delight and would challenge any refractor. Thermal equilibrium is vital for large scopes and of course seeing is king with any viewing of the planets.
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