not 100% sure but I think the link describes the great debate of Focus line not great for everbody, but I think the Sham Focus line over writes some of the casters self shields is your main question.
You should read the mesage by Sunaeri LaSuin an 61 Enchanter
and some of the other messages are quite intertaing.
Like the one about MBG F07 and 1/3 peeps ran away-lol
I F07 myself, never had a Caster ask me for other spells to replace it? If they did not problem.
https://everquest.allakhazam.com/db/spell.html?spell=3454&start=0 Fendaann 67 Sham