Sorry it’s taken so long to reply (many things going on at once). I will try to keep this short and so it will not be a full answer, but it should at least point out the direction I would take things.

First, “theological development” the implication is dogmatic development and not just mere theological opinions. Certainly there has been various ideas which have gone around which could be seen as “development” but if they have not entered into the mainstream theological consciousness, so far they are “dead ends.”

Second, the question is more Christology proper and not soteriology. Anselm really addresses the second more than the first, though of course, dealing slightly with Christology. The question of primary importance is the person of Christ, who he is, and how the natures relate in that one unity. And, though I do like St Anselm (don’t get me wrong), I do think some of his “development” is actually the reverse — this is controversial and in many ways, can’t be defended in a brief response, but where I see the evidence of this is how I read St Anselm on the will.

Third, obviously ecumenical statements would be great (and there has been some work done there, of late), but it doesn’t even have to be there. Dogmatic development seems to moved from Christology to soteriology, and the questions that early Christology have found more prominence of late (and I think it is because the question of the historical Jesus has brought back questions on Christ’s humanity ).