First post here, but I thought I could help.
Jackson do supply replacement necks as I'm waiting for one for my PC1 at the moment.
However, they only do like for like so if you do order a neck you can't specify a different fingerboard wood or different shaped headstock.
Your PC1 is Made In USA, and the DXMG is made in Japan, so there is a vast difference there alone.. And if you are the original owner of said PC1, you are covered from defect via the lifetime warranty.. Most headstock breaks where he describes his are due to an accident of some sort and not a defect.. Usually a fall or a drop that hits on the tuning key for the e string causes this to happen..