I've heard good things about Mr.Supinski but it's not a book I'd be interested in reading if it's about comparing the two fisheries. I've had it up to the eyeballs with this comparison over the years, having talked to a huge number of anglers at flyshops, shows, online, etc.
Since you brought it up, the way I see it there is no comparison. The artificial runs in the mid-west can not compare to the native runs in the PNW, plain and simple. The inland lake striped bass fishery can't be compared to the real thing on the coast, even if the fish reach comparable size. Stocked pond trout are not native brookies in Labrador, brood salmon are not Ponoi missles, Chambers Creek fish are not Hoh River native submarine bucks with attitude. No matter how rationalized, these simple truths can not be changed by you or I. Nor would I want them to change. Perhaps some do?
One was put there by God, and the other was put there by man. One is the actual native fishery trying to hang on despite everything people do to screw it up, and the other is put in place by people for recreation and commerce.
This is not to say they are not both fun and worthy of pursuit, it is only to say that as far as what steelhead stand for to me, these occurrences are apples and oranges - not subjects for comparison, each with their own merits.