I, personally, think the sales success of pod filters totally depends on the perpetuation of urban legend..that they help performance based on some nebulous "figures" supplied by some word of mouth..
I have had a few bikes now that have been retrofitted with pods (not by me) and they all sucked. Not until I returned them to near stock and/or changed the carbs to something a little more modern did actual performance return to some acceptable road worthy condition..
I suppose if a very narrow band of performance is needed, as in racing and the like, pods MAY be acceptable.. but for everyday commuter type conditions..forget it...even normally forgiving Japanese bikes are nearly impossible to get right, I can't imagine how an RE would act outside of EFI.