No one has proven a super IMG, to my knowledge. So at a very minimum, we know it’s dominant, but we cannot claim that it’s not incomplete dominant and and that the phenotype for a homozygous IMG is the same as a heterozygous IMG, we don’t know that.
I’m just saying, I think it’s dominant though too.
There have also been no reports of issues with img to img pairs. So that pretty much leaves IMG to be dominant. By this point, I feel that something would have come out about an issue with the super or that the super has a different look than the het.
That is at least my thought process behind it. We could both end up being wrong for all I know