Probably not Iris tectorum

Rob, I'm not an Iris expert by any means, but it does look like Siberian Iris to me too. At a garden tour a couple years ago I was surprised at just how fine I. tectorum was, the garden visited had the white form.  My plant shown here is only in its second year after a purchase, but its making a good show of exquisitely shaped flowers, I must move this to a more prominent location in the garden.

Yes, you're right that it doesn't take an expert to see that that is not tectorum.  It certainly does look like I. sibirica, but not an expert here either.

  Iris tectorum seems to masquerade as "Iris milesii" in the seed ex's sometimes, too.