Aperture upgrade

[Film Buff]

I would like to upgrade my Aperture 1.0 to version 2.0. Apple advices to have version 1.5 in order to upgrade to version 2.0. Non-Apple vendors selling their product as upgrade from 1.0-1.5. Who is right?
Once I upgrade to version 2.0 is 2.1.1 patch is free of charge? Does OS X 10.6.1 runs with Aperture 2.0 or Aperture 2.1.1 or both?

 

[Giaguara]

1 to 1.5 should work with same license.
Then go 1.5 to 2, then to 2.x - so as with other Mac software serial for "1.x" range covers 1.x where x is any number, and 2.x for 2.x .. and so on.
As Apple sells both Aperture and Mac OS X - yes it definitely runs on 10.6.