Whatever I read, it was so long ago that I honestly can't say for certain whether it was that
  1. d/l's are machine specific
  2. d/l's can be made machine specific
  3. d/l's are optimized for the Mac doing the d/l'ing
so, an experiment...

My d/l of Install macOS Sierra.app (i.e. 10.12.0) for my Mid 2015 Retina MacBook Pro/2.80GHz/Quad Core i7/16GB RAM weighs in at 4,898,350,695 bytes; will somebody who's got the same d/l archived please post what they've got along with the details of the Mac to which it was d/l'ed.

Thanks.

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In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire