I have a 100mm dome custom made for the 15mm Sigma lens, also the lens shade was shaved down somewhat. I am quite happy with it, I use it for almost 100% of my WA photos. I used it with my D700 in Subal housing and am now using it with the D800 in Subal housing.
A couple of examples:
Where can you have a custom dome made? That must of cost a few cases of beer!