So, I read this and decided to try out the wing design and provide pics.
Here
(note that the rest of the MOC is pretty much a throwaway, not really intended to follow your design since I have neither Gresh nor Nektann, but I tried to make it Hahli-ish regardless)
When the wings are flared, they actually do look very good, particularly from the front (as seen in the shot in the top-lefthand corner). The main drawback is that they aren't quite as appealing when lowered/"put away"; Hahli's original build did that nicely, and methinks implementing something similar works reasonably as an alternative. Even so, it would be just a small set, so it'd still be a good setup for such a set, methinks.
Also, as much as I like Nektann as a set, I also very much like the idea of Hahli taking his place. As usual, your design for such a set is truly wonderful and a nearperfect reflection of the old one.