One of the things that we as the all grain brewer using any false bottom system needs to keep in mind is that we ourselves (the brewer) create the most of the filter.
The false bottom and our silicone gasket that seals up to the side walls is just a tool to be used to keep that filter above the drain port of the kettle or mash tun. Knowing that ANY grain that is dumped on top of the false bottom can get through if it's smaller than the holes in the false bottom.
It’s our job as the brewer to get it out from under the false bottom system during the vorlauf process. To do that we need to crank up the flow to set the grain bed. This will create a higher flowrate under the bottom and help get that grain out of there. Then dial back the flow for the Sparge process as needed for your system.
We have had nearly universal consensus from people writing in about their brew days with the InfuSsion Mash Tun that they are getting clearer wort out into their brew kettles than prior systems they used and better efficiencies (by a lot).