I participated in some exchanges here on A'gon threads with Dale Harder a few months back, but not recently.
He seems most knowledgeable regarding what it takes to get a pure Walsh driver like those found in old A's and F's operating properly and has shared that info in the form of a guide both here on Agon and on Ebay. It is an extremely challenging task to accomplish in practice, as I understand it. I have also seen ads he has posted for both Ohm As and Fs here on Agon that he has completely refurbished for $5-6 grand (about the same price as a pair of new Ohm Walsh 5's) and they looked very nice. Would love to be able to hear them someday.
The closest things to Ohm As and F's today design wise are probably the larger and extremely expensive German Physics designs and Ohms own Walsh line based on the CLS driver.
I have heard most all Ohm box speaker designs from that era but never As or Fs so I cannot comment on their sound other than saying that many who did hear them remain dedicated.
Newer Walsh CLS speaks are definitely easier to drive (though the larger models still require very good amplification to do their best), are easier to locate relative to walls and are less problematic and more reliable overall.
The newer Ohm CLS speaks have better specifications on paper, but I have heard some Ohm F fans state that they do not think the newer Ohms have the same "magic" as the Fs.