By the way, I seem to remember that Teodorsson states that the raising to [i:] also failed to affect pre-vocalic <ει>, which might support this. To round off the question we need only to determine whether spurious dipthongs in pre-vocalic position might have introduced that [j]-glide too analogically - but could spurious diphthongs actually ever stand in pre-vocalic positions, word-internally? If not, the matter might be settled.