assuming I would ever be offered such a big project I would likely having to work in a team. As there aren't that many other d programmers I've met it would likely be in jave or c# (maybe c++). I would bring d up though but it will only be taken seriously if availability of other librarys aren't an issue. I wouldn't be afraid of the more complex functions as long as it's self-explanatory assuming another programmer is going to read it later and as there is a high chance he can't program in D.
I do think dmd is a capable compiler as walter bright has a lot of experience with writing compilers. Right now the eclipse plugin for d is working very good and keeps getting better.
