I am conflicted about making Darwin a primary platform. A primary platform is not a hammer with which to make other developers fix problems important to Darwin. Darwin definitely is popular and widely used. However, maintenance of Darwin in the FSF repository has been very inconsistent. Apple, like every company, has limited resources and must choose when and where to apply them based on business needs. The schedule of FSF GCC development has not always aligned well with Apple's schedule.
I would be in favor of making Darwin a primary platform if such a change would encourage Apple to make more of an effort to engage FSF GCC development and maintenance. Can GCC get such a commitment? Without such a commitment and follow-through, I am not sure whether the potential reward of greater involvement from Apple is worth the risk of unfixed problems dragging down GCC releases. David