TheVelvetGlove,
You are looking for a subjective answer to a rule which is essentially objective. It might be better if you highlighted the more important part of FAR 135.207:
"visual surface reference, or, at night, visual surface light reference, sufficient to safely control the helicopter."
Clearly a prescriptive rule would not work in this case because it depends upon a number of issues - not the least of which is the handling qualities of the helicopter. The external references required for 'safely controlling a helicopter' with an autopilot is not the same as those for a basic Robinson R22.
The rule calls for an exercise of judgement; clearly you know the issues but are you exercising good judgement?
Jim