[Frank12us]

... which presumes that with regard to reloading at intentionally low pressures (5K to 8K PSI) a fluffier low density flake type powder will be in general more accommodating of such low pressures (as regards maintaining consistent pressures and velocities at various extremes of temperatures) than would be the case for the various of denser ball type powders?

No. Chemical composition introduces too many variables (single base/double base/retardants/etc.)