This is the way I see it. I could be wrong, but these are the thoughts I have always held with respect to flaked salt.
I believe that the advantage of flaked salt, used in a dry-salted curd cheese like cheddar, is its relatively large surface area to volume ratio. This property allows it to melt or dissolve quickly and evenly into the cheese curds.
Compared to flaked salt, a course grained salt would not dissolve as readily.
I happen to use canning salt for my cheddars because it does have a high(er) surface area to volume ratio than does a course grained salt. And because it is not iodized. I realize that its not ideal, but I cannot readily find bulk quantities of flaked salt.
If I could score this: http://www.mortonsalt.com/products/industrial/Topflakesalt.html
I would be very happy. Actually, this would last me forever and I would be looking to split an order like this about 8 ways.
Actually, I use canning salt for both my cheese curds and my brines..
I could see using a course grain salt for rind preparation or brine prep.
I'm sure LB will let me know if I am off track here.