Having lost the EPC to Mota-Engil (Vale's buddy in Africa), I don't think China is going to shoot herself in the foot again.
For China, securing Mbalam-Nabeba is much more than the mere economics of a $21/T DSO resource (prospective for losts more) or a $42/T Ibaritite resource good for 100 years.
It's the political influence lost in Central Africa in what is the single most important project for Cameroon and Congo for DECADES to come.
Hence, any offer will take that into account.
Perhaps, that's why the Chinese wanted is to know this at the beginning of the year:
http://online.wsj.com/news/articles/SB10001424052702304007504579348221352253640