I read most of this very long post and learned/laughed...
I am wondering if a large stainless steel filter (of ? microns) could solve a lot of the sediment passing through issue?
I was thinking of a large pot in stainless steel with filters only on the side (starting at 1-2 inches) so that the sediment could stay at the bottom and the rest could mix freely?
Nah, doesn't really work. If the filter, be it metal or cloth, is fine enough to give you good wort clarity, its fine enough to clog very quickly indeed. It works OK, if you have multiple hours spare to stand around and wait for the bag to drain. Earlier in the thread someone started out using a very tight weave polyester cloth - clear wort, very long drain time.
Having the sides a "loose" mesh and the bottom a tight one is a nice thought to try and beat it, but really, your solids and stuff are all through the wort, that solution may well be a little "better", but I seriously doubt it would give people who are nervous about cloudy wort a result they would be happy with. worth a try, but expensive if it ends up not doing the job.
Its just not really a problem though, I know people assume its "flour" but its not, its mostly protein. Just bog standard break material that would normally be trapped in the grain bed of a mash tun. Do your boil and leave it in the kettle with the rest of the muck. You'll still be getting total efficiency as good or better than the average batch sparger.....
I've tried quite a few "variations" of the simple BIAB method over the years - In my experience, all of them make your life harder & none of them make your beer better.
edit - I just realised that you are (i think) talking about a mesh filter for the post boil wort rather than a replacement for the bag. That would work... but not really any better than say some of the current wort filters out there like the hop stopper (which btw I can see no reason would not work as well in a BIAB system as any other) and seems a lot more expensive and intrusive an option. At any rate - as in any other system you can just do a whirlpool. It all depends on just how much you begrudge the extra litre or two of wort that will cost you vs the best you will be able to do.