I also ordered my new iMAC and plan to use boot camp for Win 10.
I am kind of worry about such Win 10 driver issue in bootcamp because I already read it from several users. So far, all best solution is re-do the boot camp again, and indeed it solves the issue in most cases. I am very curious why "re-do" bootcamp will make differenct? same hardware, same software, same bootcamp procedure, why different results and why can't it be perfect installed in the first time?