How to pick a winner when choosing a PM graphite

In discussions of alloying additives for improving PM manufactured parts the role of carbon is often overlooked. However the role of carbon is crucial in two key respects. First, carbon assists steel matrix hardening by diffusion into iron particles. Second, it decreases the co-efficient of friction by solid state lubrication. Swiss/Italian research has looked at how graphite type and particle size distribution can affect flowability of the mix, dimensional change after sintering and mechanical properties of PM parts. So how do manufacturers select graphite powder when considering their process metallurgy?