If it's worth your while to search on that other forum (the slow one) you can probably find the post within the last year or so concerning an end-plate experiment in which a modeler fitted removable end-plates, trimmed the plane with both end-plates on, then removed one and flew again. To get the model re-trimmed in the roll axis he reported two clicks of aileron correction were necessary. Two clicks is not a whole lot, but it is a more tangible result than many other popularly debated design mods.