developers to use the best style possible.
I was thinking about this earlier; to leverage the phrase 'best style' presupposes that the ranking can be achieved at all. Which I think is part of what you refer to regarding too many variables. The other part is a normative valuation. A morally valuated assessment.
I'm not at all sure that one can gain consensus on morally praiseworthy or blameworthy approaches without appealing to other principles around what are the characteristics of a good or a bad route or a good or bad experience establishing the route. The ethical approach dictates the values? Or the values the approach?
I'm of course assuming that true moral relativism with regard to FA principles is anathema unless on private property and maybe not even then. Not everything is permissible, both because there are many participants with a vast set of moral predispositions, but also because of the externality of land management. E.g. in the extreme, NPS won't permit spray painting on all routes the names and ratings, or chiseling Mungeclimber's good looks into the side of El Cap. And even on private property using harsh chemical solvents to defoliate can still be illegal to prevent ground water contamination.
This always brings me back to climber's who say "I'm attracted to climbing because it has no rules." - That strikes me as being ignorant or deliberately uncaring of others in the world. The former can be educated, the later go to jail eventually.
So back to the "best style" - I prefer to distinguish 'style' as those actions which have no direct impact on other climbers. Whereas ethics and 'ethical approaches' deal with things that have an impact on other climbers, namely fixed protection.
So the question might be better phrased as 'what are the characteristics of the best ethical approach to establishing fixed protection'?
This depends on goals of the route.
If my goal is a great personal experience, then whatever makes that experience great will satisfy the standard.
If the goal is a great route for the community of climbers, then whatever makes that route great will satisfy the standard.
...more later...