The membrane size (circumference) is the same because the media bottles are always the same size (45 & 33, I think those are the actual opening sizes, apologize if I'm incorrect there) so, in my mind that lends itself to the idea that IF the volume was dictating differences in filter it would then have to be a thickness change.Would a .22 250ml vs a .22 500 or 1000ml filter membrane be different? I assumed the only difference was the capacity that the funnel itself holds.
Without having clear evidence, I would say it's relatively safe to assume that those units can handle more than advertised.
Not gospel folks!! Don't listen to me!!