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In an open air environment a compound scope will perform better overall only if the optics are at ambient. Often people talk about refractors being able to cut through the seeing, however one can never really know what the seeing is unless the optics are at or very near to ambient temperature. This is of course where the problem lies. No scope larger than 10 inches will be at ambient inside 4 hours without active cooling. Even with fans the mirror gives off heat for hours.
I have never seen a scope affected by the body heat of a person in an open air environment. It can happen in a dome observatory. The position of the focusor is irrelevant and the real issue at hand is the heat of the mirror.
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