I fully agree on the QT as well, But for most of my fishkeeping life, I didn't have room/money for a dedicated qt tank. I use the 10g snail breeder as that now, and when the basement is done, I will have a 20g dedicated to qt only.
The real comparison for me with the salt and ich came with my pictus cats which are highly succeptable, as well as hard to treat. With pictus, Ich can be fatal very quickly and ich meds can be fatal just as quickly. these fish just don't seem to handle stress well at all. My pictus were obviously stressed during the treatment, but continued eating and came through quite well. they didn't show nearly the distress signs that I got when using the ICH method. I haven't tried it with cories myself,, but know several people including my Brother who have successfully cured ich on cories with the salt/heat method.
Dave