Maybe I reinvented the wheel and subbing butter beans for spuds in potato salad is the national dish of Pashminastan, but I had the inspiration to do this and like the results. I soaked and cooked "large dry lima beans", which is the dry version of what's called butter beans if they are canned. Note: this is NOT the same pale green lima that is sold frozen on its own or in succotash. The larger, whiter bean is mild and creamy. I've adopted Cook's Illustrated's method of putting the vinegar and/or pickle brine onto the hot potatoes to season them, and wanted the same seasoning effect with the beans, so I boiled rather than simmered for part of the cooking time, in order to make sure the skins split. I assume that the brine won't permeate intact skins very well. I liked the end result very much. Blindfolded, I'd have a hard time telling this from regular potato salad. More protein and fiber, and I assume the fauxtato salad won't spike blood sugar the way potatoes do.
Next time I will try navy beans, for the sake of quicker hot weather cooking time. The texture won't mimic regular potato salad, though. I will try canned butter beans for German Ersatzkartoffel Salad, because in this case the liquid in the can should be a partial shortcut, standing in for the flour thickening.