A paper by B. Baker et. al. from Special Metals Corp., USA and S. McCoy of Special Metals, Wiggin, UK. presented at NACE 2002. The paper number is 02394 which can be obtained from NACE.
These authors looked at a great number of alloys under a laboratory setting from 593C to 796C [the critical temperature range for metal dusting] and the data shows Alloy 601 has only slightly better metal dusting resistance than Alloy 800. Alloys such 693 and 671 to name a couple alloys, show excellent metal dusting resistance up 16000 hours in a laboratory setting. In general terms alloys with higher nickel levels show greater resistance to metal dusting.
One alternative to Alloy 601 that has worked well in a ammonia producing facility [exit end of the process gas cooler] is Alloy 625 which has shown better metal dusting resistance than Alloy 800. In the Baker et. al. paper the laboratory data shows metal dusting resistance of Alloy 625 and Alloy 601 is about equivalent. However, Alloy 625 is stronger than Alloy 601 at elevated temperatures so choice depends on the end application.
Ferritic alloys maybe better at metal dusting resistance, but DO NOT have the oxidation resistance needed at the temperatures involved.