Nacets for me as well. Sometimes Gillette yellows.For head shaving a mild open comb is ideal. A mild razor will be much easier to use and the open comb won't clog on longer growth.
The Merkur open-comb head design is just about perfect for head-shaving (all their open comb models use the same head).
PS: I use mine with Nacets. A sharp blade in a mild razor is a good combination.