I have been using the poly_survey_adv. I think you meant PolygonSurvey instead of poly_survey? These are quite different in regards to the why the flight is done. I am not sure that PolygonSurvey is useful really. Also I think we should remove the "adv" word, I wouldn't say one is more advanced, they are just different. So what you say of having only one would be a good idea and I would propose that the one you use is poly_survey_adv. If someone thinks PolygonSurvey is useful then I think there could not be just one and new names would be required to differentiate them.
The poly_survey_adv is good when there is strong wind because you can fly slowly into the wind when taking photos then the return trip in the direction of the wind is not used. If there is not much wind then the return trip is just wasted. I am not sure if this can be fixed and keep just this one function or this one can be kept for strong wind and a new one can be made for when there is no strong wind.