Wilson remixes are never anything less than an improvement. He really has an ear for making large instrumentation/many overdubs sound transparent. Chicago is in so far unusual as he is generally associated with remixes of "true prog": Caravan, King Crimson, ELP, Jethro Tull. But to him, he says in the liner notes, Chicago II was an eye-popping Prog album when it came out in 1969 - and I guess it actually was at the time.
I have never considered Chicago "prog" but I guess I'm guilty of considering prog as something very British: That idiosyncratic mix of complex music and commercial appeal seemed to happen mostly on British turf.
It's hard to come up with US bands comparable to Jethro Tull, Genesis, Yes, Pink Floyd, Emerson Lake & Palmer, King Crimson, Supertramp, Gentle Giant, Camel or Caravan in complexity and commercial appeal - the nearest I can think of is Kansas, but even they were always rated by me as "complex AOR" rather than prog which is doing them injustice I think. That is not to say that Yanks can't play complex music as one listen to Captain Beefheart or Zappa will prove - or Return to Forever if you want to include the jazz rock offshoots. And there were of course US bands such as Utopia or Starcastle who undoubtedly played prog music, but did not have the commercial relevance of their British counterparts.
I guess Rush fit the prog bracket and Max Webster, but while North American, they were both not US bands.