i think it would look pretty odd more because of how big an iris usually is than anything else.  the geometry has a visible effect on the realism i'd like, but not so strong of one that i'd be likely to describe a moved edge as "pretty odd" myself.  not nearly as obvious as say,  missing the edge of a lip, and i've got at least one successful render where my totally inexpert morph moved the physical edge of the lip and the texture i used was pretty far in from the edge anyway.

but it's moot.  i was responding to the ongoing conversation about needing some sort of transparency and special geometry to achieve an iris with a realistically soft edge, when that's only needed when you've separated the iris from the scelera.  i guess it could even be different materials, as long as it was one contiguous UV map.