Sorry for the late response....just finding this.
I was informed that the RT1500 was replacing the RT1200 and it would occur in the next 30-60 days as well.
Dillon is not making the 300 toolheads or the 300 trim dies, both of those are from GSI. The GSI dies are a two stage with a rough die and a final die. The guys I spoke to at the Dillon booth said the tests they have done were using the final die only and had hit 500,000 pieces without issue.
Also, not sure where they idea came from that you cant mill down the cast toolheads on the 650...many have done it, myself included.