I brew with a Sankey mash tun with a false bottom that sits on the transition from the side to bottom. This results in about 2 gallon beneath the FB, but that doesn't bother me since I drain the tun from the bottom.
My issue is my free FB is 1/8" holes on 3/16" centers. Because of the rather large holes I lay a piece of aluminum window screen on the FB to minimize grits being carried through.
I like the idea of a new domed 12" diameter FB that would sit a little lower, but need to be convinced it is worth the $50, or so, that it will cost. Any idea what the hole size and spacing is on one of them?